Since your 60 doesn’t have headlight washers, I’m gonna guess it is an early 60. If it is, a 5 speed swap is not as easy You may need to get a later split case for it to work. I’m just guessing though. I don’t know s*** about cruisers.
Head gasket, Desmog, rebuild carb and put in a 5 speed
If you can sell a kidney and get a little more money:
1uz or LS, depends on how much work you’re gonna do yourself.