Pontiac to Chevy engine swap

I'm gonna be putting an LT1 into my '70 firebird and was wondering what motor mounts I need for the frame side. I havent done any research yet but I'm guessing that the stock Pontiac mounts won't work with the engine side mounts on the motor itself. Do I need to go to the junkyard and get some 2nd gen camaro mounts, or is there any way I can use the frame side mounts out of the donor car (since I have the whole K-member still)...

If the LT1 uses the same engine mount pattern as the classic sbc (and I think it does), then you need 70-71 Camaro mounts. These years still used the old style motor mounts that had the rubber on the portion that bolts to the engine. The frames of Camaros and Firebirds will be drilled for both chevy and pontiac mounts. So the easiest thing to do would be to obtain 70-71 frame and motor mounts.

72 up went to the clamshell mounts having the rubber portion on the frame. I've never tried to bolt 72 up mounts on a 70-71, but I don't think they will have the pattern match the frame holes. Pontiac mounts won't work for sure on the LT1.