Although not the worst since they kinda blend in. I would agree get rid of the lights as well. There are good mustang lights with black housings... Not sure how much that door kit costs, but im sure if you take it off and sell it(which should be easy since there are others in your area), then youve prolly got a decent chunck o change for a swap.
Checked out the pics, minus the badass ones with you on ur car lol the car is clean.. I see you were thinking of a 351 out of an old Shelby GT350, am i correct? If so, no good here boss..
Also i dont know how hard it is to swap a v8 into a v6 body, one of these guys might.. But if you play your cards right, im sure it could be done cheaply(not the work but you know what i mean), or sell your stuff and start with a v8 car. Your in FL, you should be able to find another car like yours with a v8 that is just as clean and well taken care of for a decent price.
Otherwise keep taking care of yours, keep it clean.