The shaft length is the same between the caddy an chevy but the body is a different length and diameter where it drops into the block. Because of the larger diameter of the HEI cap there is a few inches between the block and body to clear the AC compressor. Another issue you may have if you still have the AC compressor is that the inner of the dual belt will rub on the cap. When they went to the HEI they switched to a wider single belt to clear the cap. If you are not running the AC anymore you can just remove it and run a shorter belt(s) straignt from the crank pulley to the power steering pump. It will clear the water pump fine. If you motor has the smog pump you will also have to put a slight dent /bend in the tube that goes between the heads. A few of the performance people make dizzys for these motors. The 472 68-74 ,500 70-76, 425 77-79, and 368 80-85. Were all the same basic block so the dizzys will interchange. The basic HEI got phased in starting in 74. All 75-79 were HEI’s with mechanical and vacuum advance. Starting in 80 some of them were computer controlled timing so they did not have the weights. 75-79 there was an EFI option for those motors the top side of those dizzys is the same only difference is there is a sensor in the stalk that gave a tach signal to the ECU to fire the injectors. Only other catch is the 75-80 seville and 79 eldorado used the 350 EFI Oldsmobile motor so those wont fit your 472.

Hope this helps