i need help with a few questions

[59 camaro]

i bought this 58 gmc a few weeks ago and im trying to just put it back on the road, plates have been expired since 1987 so im assuming it hasent been driven, i got it off this old man who had it in his back yard for a long time.

anyways, plans WERE to buy an apache and dump a LS1 in it buuuuut i just cant see myself ****ing up a GMC and more bcus its a automatic... truck is pretty complete and its a fleetside....

so i already rebuilt the brakes all around, new master too.... now i checked the oil on the tranny and the motor and it looks like BRAND NEW... i took the carb to get rebuilt.... it still has a generator too... this idiot added 2 under the bed gastanks i want to remove but it still has the og tank behind the seat...

questions,

i bought everything to do a tune up, but anything else i should rebuild?

what do i gap the sparkplugs?

should i upgrade to a alternator or leave it original with a generator?

how the hell do i remove the chrome trim around the windshield and the rear big back window?

i want to lower the front 1-2 inches, should i just remove leafS? if so how many?

anything i should do to the tranny? the guy claims the tranny was rebuilt back in the days

i plan to lower the back 7 inches and cnotch it, should i go monos? or dearched springs?

i plan on sanding the old patina and spraying clear on it, whats the best way to do this, i want the old look to stay on the truck

im sure im forgetting a few questions but thanks for reading and for the help in advance, and if anyone by the ANAHEIM area wana come help me feel free to lmk lol