I have a 71 olds cutlass S with a 350 4-barrel that I am making into a 442 clone. I found a 455 (C heads, Edelbrock intake/850cfm carb, headers) and I need to figure out what needs to be changed to get this to fit and work for my car. I have been made aware that I need a new radiator, a new transmission was advised for if im hard on it, but I was curious on the mounting etc.

Anyone dealt with this before?

 

Use the search feature and you'll find tons of stuff on this. It should be a pretty straight forward swap. Biggest issue is that if you use the small block frame mounts then use the small block motor mounts and vice-versa. You'll also want notched valve covers as well.

 

The notched valve covers are not a necessity, they just give a little extra clearance.
Use the 350 engine mounts, water pump and all of the pulleys and you'll be good to go. Just get the longer alternator belt for the 455 in a 71 and you should be set.
Also don't loose the spacer for the power steering pump lower bracket that bolts to the side of the block. That can be a MAJOR PITA to replace.

 

Inline Tube repros these now (power steerign spacer). I just replaced my lower one (from a stack of washers) recently when I was detailing the engine compartment this winter.

 

Did this to my Vista Cruiser a couple years ago. Easy swap, just use the SB motor mounts and you will not need to change the frame mounts. If you have a Turbo 350 tran, you may want to find a 400. I also changed the radiator, but I'm real sure I would have had to. Also you do not need notched valve covers, I also have AC and the fit, little tight.

 

It is correct that you do not NEED them. I just prefer the clearance and the factory look. Hence the "want" and not "need".

 

My 455 did not come with exhaust manifolds so headers were installed. This has a list of mods if you have go that route.