Nate...
3-4K will get you more than just a motor.
looking at 4-450 at the wheels is nothing a solid stock bottom end can't tackle.
Tuning will be an issue, but nothing MAFT-Pro can't handle.
Purchasing a good bolt on turbo will require around 1500, and you can leave most of the fuel system stock, save a fuel pump and good afpr. If you really want 450 rather than 400, go with 550s.
What I would do, and probably get smacked for doing:
rings rod and main bearings from toyota, $350
Full victor reins gasket set, $175
Sell oem headgasket from kit -$30
ARP head studs $105
Cometic headgasket $150
Hone block, surface block, surface head $200
Plastigage $2
Moly assy lube $8
That's it for the long block. $960, call it a grand.
ok, 2-3K left. I'd go with an internally gated gt35R for roughly $1500
Then you need an adapter and oil lines, etc... Loking around $250 for all of that.
So you're left with 1250. you already have a clutch. That's good.
Maft-pro speed dens is $650 or so,
550s go for about $350
walbro for $100
AFPR for $150
More lines from the hydraulic shop for $100
so, you end up 100 short for those misc parts you'll need to get her running.