[Yukon Jack]

I read up on this subject prior to putting a 454 in my 69 K20. Generally I read you could use your original crossmember/towers and motor mounts and you would have to bash in the firewall a bit. Also read some said a minor body lift would give you adequate clearance. Others said all you have to do is move the engine forward a bit. Using a newer engine crossmember is supposed to make life easier if you are going with headers.

I went with doing a body lift and at least for me a 2" body lift did not give adequate clearance at the firewall using the stock crossmember/towers. I had to go with a bigger body lift and still had to modify the firewall considerably.

I will move my engine forward in the future and I think that is the best option. I think moving the engine forward 1 1/2 to 2" forward should be sufficient.

I have seen pics of trucks where the owner states it is in the small block position with minor firewall massaging, but for the life of me I can't see how that is possible after seeing the amount of firewall interference I had.