Hi all, I’ve recently gotten the opportunity to swap my stock 350 small block motor for a 454 big block with about 350 hp and 410 torque. It should drop right in in terms of engine room and bolting it down. My question is if the stock transmission will be able to handle that power and should I maybe look into heavier front springs. It has a turbo 350 4 speed manual trans if I recall correctly

 

Well this makes no sense,a Turbo 350 is a 3 speed automatic not a 4 speed manual,that said it sounds like a mild 454 so you'll probably be alright if you are using it as a cruiser,drag racing it would be another story especially with a 4 speed stick and you might want to upgrade the rear end as well.
The 454 engine is externally balanced so you'll need a different flexplate (automatic) or flywheel (manual),your starter shound bolt right up but may need shimming to mate to the ring gear properly.
You will need new motor mounts for the big block on the engine,not sure on the frame member with a 2nd gen but possibly for firewall and steering box clearance.
On 1st gen cars you need a different heater core to clear the cylinder head in a small to big block swap,I don't think that's the case with 2nd gens but I've never done one so I don't know for sure.
I'd wait on the springs until you have the swap done,I did the swap on a '69 and never changed them,see how it works out first.