1st thing you should do is add a larger size wire from the batt + on alt to junction block on firewall. You should be able to find 100+ amp cs130 alt in Panama, they came on 1988-1999 trucks. switch the pulley with your alt. you will need to modify the small 2 wire plug to fit or buy/make an adapter(Ac Delco pt2145). You also may need to clock, or change the orientation of the back half to the front half to get the wiring, esp the batt wire to clear the engine and valve cover.
@500$k5 owns an auto electric shop, he built me a nice CS130 with heavy duty bearings, clocked for a gen 1 chevy and make 140 amps. The cs130 charge better at lower rpm than the factory 10si
also the cs144 is another option mid 90's GM vehicles came with them and many were 140 amps.