http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1824241858

Were they really two versions of the E-88 head? And if it does exist is there really a big performance difference?

Yes, there were two versions of the E-88 head. I believe you will find all the answers on heads on the Z gararge web-site in the links. Brian does an excellent job of covering the different heads and giving the pro's and con's of each one.

Yes, there are two E-88 heads. An early, desired and a later one.

I have a 72 240Z (manufactured in October of 1971) with the early E-88 head.

The Z garage notes that one version came with smaller valves and larger valves? If the performance increase very different from the two versions of the heads?

The differences would probably almost hard to tell by the seat of the pants method. The early version had more compression, and smaller valves. The later version had larger valves yet had slightly lower compression. On their respective engines it would be hard to differentiate between the two.

The only way to tell would be to put both styles of head on the same short block and test it that way.

Do you guys think this is a fair price for that head with what it comes with? I might be able to use it considering my head might have faulty valves... A compression check on my engine was like 135, 75, 55 ,35 35, 75. My dad told me could be bad valve, but then I guess it could also be bad piston rings or head gasket... oye... but I guess if this is a good deal then it might be worth the money to have a head ready to go (According to the post) and for the compression increase. Think it's a good deal?

Well, the price is fair. I wouldn't go much more than 200 for a used head since you have no way of knowing exactly what condition it is in. Z heads were susceptible to warping and cracking from overheating so you might ask if you can have a machine shop check the deck on the head for straightness before you pay for it.

Sorry to say this but with the compression you described you may have more problems than a head. Sounds like the rings may be one thing you need to check over, when you have the head off be sure to check the cylinder walls carefully for any galling or scratches. You might want to borrow an inside micrometer if possible to check the bores while you have the head off. No sense in wasting the time putting a different head on with a new gasket set only to find the compression isn't much better.