[gman26]

Changing to HEI distributor and I need wires; since they don't have a set for a 70 Cat, what other car would do? Any suggestions?

["QUICK-SILVER"]

Cat doesn't have anything to do with it. It's just HEI in a traditional Pontiac V8 engines from 75 to 78. Some 74s and some 79s had it, but that's something else to get them confused at the parts stores.
350's, 400's, 455's all have the same outside dimensions, so plug wires should be the same even in the different body styles. 75 bonneville 400 should be the same as a 78 400 firebird.
Just take your pick on year and body style and go for it. Like a 76 455 grandprix, it'ld be hard for them to mess up on that one.

It was nice when the people at the parts stores actually knew cars. A kid asked me one time if my TA was 2 door or 4 door, when I told him they didn't make 4 door firebirds, he looked at me like I was the dumb one.