Have found a rebuilt '75 L28 w/o carb. Will this bolt up straight accross to my '73 240 automatic ? Anybody help? Thanks.

Should bolt in with no problems. You will have to use the flex-plate from the L-24 and the intake and carbs, but that shouldn't be a problem. I have no experience with the automatics, but it seems to me if the flywheels are interchangeable the flex plate for the autos should be too.