I bought a 1974 260z this past weekend and along with this Z came a non running "parts" Z that had a ton of extra parts, motor and transmission. My main question to everyone is this.... My '74 260z appears to have on its stock carbs but the parts Z had 2 sets of different carbs: flat tops from another Z and double barrel webber carbs on a cannon intake. What is the best choice for me knowing I will have to rebuild the 2 extra carbs?

Is that dual Weber 32/36DGV? If so, I think weber is the your best choice for performance. SU is smoother ride and economically good choice.

Are the Webers DCOE (sidedraft) or DGV (downdraft)? If DCOE, then use the Webers. If DGV, then don't even think about it. Otherwise, I'd say flat-tops but good luck getting a complete rebuild kit. Sourcing a good set of round tops would be the other option.

The webers are a DGV for sure. I didn't think that the rebuild kits would be too hard to find with all the research that I have been doing and seeing the different companies and places that rebuild them for people. I kind of assumed they would also be able to sell the kit and THEZSTORE.com seems to have full rebuild kits. Are those no good? (not sure what the 32/36DGV stands for)

DGV's are OK carbs, but they have a reputation for being unfriendly to tune beyond bone stock, and not always the best for economy, either. I can't think of a single case where I'd prefer DGVs over a pair of roundtop SUs.

I'm vizualing a parts car full of stuff among them more than one choice of carbs rattling around therein. My point, right here right now, is that in order for any of them to "function" at some level, you should be looking down the gun barrel of having them (some or all) gone through before even giving them a try. Old gamey nasty dried out carbs will most assuredly be a crap shoot when pressed into service. Just saying.....

I'm vizualing a parts car full of stuff among them more than one choice of carbs rattling around therein. My point, right here right now, is that in order for any of them to "function" at some level, you should be looking down the gun barrel of having them (some or all) gone through before even giving them a try. Old gamey nasty dried out carbs will most assuredly be a crap shoot when pressed into service. Just saying.....

I completely agree with you. I planned on having both the sets of spare carbs rebuilt before I try to install anything and then sell of the others

The webers are a DGV for sure. I didn't think that the rebuild kits would be too hard to find with all the research that I have been doing and seeing the different companies and places that rebuild them for people. I kind of assumed they would also be able to sell the kit and THEZSTORE.com seems to have full rebuild kits. Are those no good? (not sure what the 32/36DGV stands for)

A full rebuild may require things like throttle bushings/bearings, power valves, and other hard-to-get parts. A typical cheap-o rebuild "kit" will probably have a few gaskets, o-rings and needle valve. However, I'm not too familiar with flat-top rebuilds so someone who's done it would be more informative.

The 32/36 DGV is a "progressive" carb. The 32 is the main venturi diameter and 36 is the secondary venturi diameter, in mm. The DGV feeds the engine with the 32mm venturi until enough demand opens up the 36. They are also downdraft carbs, not desirable in an inline engine configuration.

DGV's are OK carbs, but they have a reputation for being unfriendly to tune beyond bone stock, and not always the best for economy, either. I can't think of a single case where I'd prefer DGVs over a pair of roundtop SUs.

I'd prefer a good set of flat-tops to DGVs, hands down.

DGV's are OK carbs, but they have a reputation for being unfriendly to tune beyond bone stock, and not always the best for economy, either. I can't think of a single case where I'd prefer DGVs over a pair of roundtop SUs.

I was hoping for more of a comfortable ride and the old owner of my running 240 said that it was a real rough ride and he had to gas it a lot to get it more smooth

A full rebuild may require things like throttle bushings/bearings, power valves, and other hard-to-get parts. A typical cheap-o rebuild "kit" will probably have a few gaskets, o-rings and needle valve. However, I'm not too familiar with flat-top rebuilds so someone who's done it would be more informative.

The 32/36 DGV is a "progressive" carb. The 32 is the main venturi diameter and 36 is the secondary venturi diameter, in mm. The DGV feeds the engine with the 32mm venturi until enough demand opens up the 36. They are also downdraft carbs, not desirable in an inline engine configuration.

I'd prefer a good set of flat-tops to DGVs, hands down.

then flat-tops is will be. Everything that I have seen has pretty much said the same thing