Well you have the car so you can change your mind whenever you like. If insurance gave you 4800 then that usually means they probably guessed it would have cost at least 75% of that cost to fix. So probably at least, or over 3600 to fix. Probably more because that is ignoring the salvage value of the Supra.
Keep in mind...knowing people that can weld doesnt mean you should have them working on your car. I am referencing the welder. I am not saying it is a bad idea....BUT just be wary unless you have confidence in them.
How available are your reconstructions recourses, such as your welder?
This car does look doable, I think a GOOD shop will charge a lot more than 1200. Part REPLACEMENT is better than straightening. If it is available...
Alignment....is important. That was a real nice car and do you want it looking like the thousands of shitty 240's that have had bad body-jobs done? Mis-aligned panels that are too close or too far....etc.
Keep in mind the other things...stripping it...painting it...sanding....clean scum and oil...reassembly...repairing... All of those add up. Even worse when you cant find the parts or hardware you put somewhere.
I probably sound partial to buying another Supra. I am not, just aware with what it takes cause I fucked up my truck and did that. I bought OEM sheetmetal though, so a lot of the prep was a cakewalk. Granted the hood, apron, core support and fender cost about 1000 dollars unpainted. Oh and paint is expensive. Just to paint those panels and clear was about 200 on the cheaper end.
I believe you could probably do it for a couple thousand bucks or less, depending on your route. It is a LOT of work. Even more so if you want to tack it, then assemble the panels to check for the alignment of them. If you cannot buy new OEM panels, another donor car clip is probably the best idea. I am a little skeptical on 'OEM replacement.' THey generally use slightly thinner, lower grade metal. I would not have confidence in their supposed 'meets or exceeds OEM specifications' statements. Otherwise aftermarket Tacoma rotors wouldn't always warp (3 sets out of shape...from the first mile). I measured one, on that topic. It was about .45mm thinner on each pad surface compared to a expensive-ass Toyota rotor...that has yet to warp. They also rust much quicker, I noticed. Sorry, a little tangential...I do that.
Good luck.