Hello to everyone on the forums, this is a great and well informed and knowledgable group on people. I have been on the forums for a little while, and is my first question so please be easy on me.
I'm trying to build my 72 Cutlass with a 350 rocket and Th350 trans. I have an opportunity to get a running 425 w/Th400 out of a 67 Olds 98. My 350 needs rebuilding. I guess my questions are is it a good idea to do the swap, and what parts are needed? I've tried a search but only can find the 455 engine swaps and haven't found any swaps to a 425 engine in a 70-72 Cutlass.
I wanted to do something a little different and plan on doing a/c later. I'm doing some suspension upgrades. I want it to be reliable but not really looking for a track car, but something I can go to car meets with the family but still will get up and go. Any thoughts and help would greatly appreciated.

 

The 425 is the same physical size as the 455 so all the info you find there will apply.
That should be a good swap. 425 will give you plenty of power.
Remember to keep flexplates etc together as they are different from your 350.

 

This has been covered to death here, so start with the Search function. Anything about the 455 swap applies, except for the unique 64-67 flexplate, as Mark noted. This is nearly a bolt-in swap.

You cannot use the trans out of the 98 for two reasons, however. First, it has a long tailshaft, but more importantly it does not have a speedo drive gear provision. The 1960s Olds full size cars ran the speedo cable from the LH front wheel. Get an A-body short-tail TH400 or just keep your TH350 until it pukes. Search the TH350 to TH400 trans swap here also, as there are some details to be aware of.

 

Thanks for the info, I guess I will do a little more research. But I'm looking more to doing the 425 swap and using my th350 trans.

 

That shouldn't be a problem...just save your money for a TH400, as the TH350 may not last as long as you would like....it is a very good trans, but the TH400 is built better for the power of the 400/425/455....425 is a great engine!