So I'm a total newbie. I have my hands on a 73 cutlass supreme with a 350 rocket. It has sat about 8-10 years with out running. The carburetor has been off just as long. The more I look into the rebuild and construction of the current stock 350 versus buying a LS type engine. The more I am leaning towards going the LS route. Can anyone tell me from their experience the pros and cons here. Keep in mind I am not restoring this car with the intention of selling it. I plan on keeping this one. Thanks

 

Is there anything wrong with the engine apart from it having sat for so long? If not, cleanup/rebuild the carb, follow some simple pre-start maintenance including priming the oil and get it running.

 

The rocket rebuild is certainly more strait forward.
But I've got 2 LS swaps, and if you're going to keep it, use it as a daily driver, you cant beat an LS and OD trans for reliability, drivability, gas mileage. BTW, my gas mileage nearly doubled on both swaps, and now I just turn the key and drive it like a newer car.
There are plenty of people doing them, so you wont have to invent or fabricate much any more. The most complex part would probably be wiring and fuel system. But those components can be bought if you don't want to do your own.
My 72 swap:
https://classicoldsmobile.com/forums...-iii-swap.html

 

thank you @Gary 68&72 this is what I'm thinking. I have done quite a bit of research on the rocket v.s. Ls and feel swapping to a LS is a better fit for what I want out of my engine, power, performance and reliability. I understand the people who want everything original cringe at the idea of dropping a new engine in a classic cutlass, but at the end of the day it's my car. I believe what I will do is remove each component of the original 350 rocket decrease paint and rebuild and sell the engine to partialy finance the new LS ENGINE FOR MY CAR. Any ideas on specific LS engine that may be more compatible to the 73 cutlass supreme. Or do almost all need a bit of adjusting to work? thank you like I mentioned in fresh at all this with a mechanical inclined brain.

 

Have a look over at LS1tech for 73+ A body swaps. Lots of info there.
Since it wont be a "performance" build, weight is not an issue, so go for an iron block 4.8, 5.3, or 6.0 truck motor. 5.3s are the most plentiful at a reasonable price.
Some come with VVT and DOD which you can keep if you keep the auto trans that comes with it. But swaps tend to be easier on motors without those. 99-07 were gen IIIs and had some year specific components, especially the DBW stuff. A lot of the 07+ Gen IVs share those things.