Yes I did have to modify the trans tunnel to accommodate the HEI and the trans clearance demands. When I got the car it had a cast iron ’65 Buick 300 which didn’t run and someone had put a turbo 350 trans in it. I pulled both and put a roller cam Olds 307 with the stainless tubular exhaust manifolds which I knew I’d have to modify to clear the steering which is the biggest obstacle to putting an Olds V8 in these cars. A double diaphragm Corvette power brake booster squeezes in there fairly well but not with a big block Rocket, only a small block. I wouldn’t have done the mods if it was a practical restoration to original but it wasn’t. Being a heater delete car from Hawaii, the clean firewall made things easier and I was able to fabricate a heater/defroster like the old cars had under the dash. The 80’s Camaro shifter works well with the 2004r.