you'll have way more than 4k in it even if people give you parts for free
k-member, new front springs, all new front drive and accesories, adapter hosuing for your t45, new clutch and flywheel, all new harness and ecu custom tune, then you have the motor itself a core is going to run you almost 500 bucks then a good crank, rod, piston combo, you need a good set of heads to make any power on a pushrod ford so expect to put 1k or better in a set of heads then your intake manifold, injectors, fastners motor mounts and I'm just scratching the surface I'm not trying to rain on your parade here, but if you have a modualr motor car keep the modualr style engine if you want to build your own motor do a 4v 5.4 you'll make all the power you want and keep your factory harness computer and accesories just food for thought
if you really want to do a 351 trade me cars I'll take your 99 for my 90 with all the bolt ons plus a 351 builder on a pallet ready to go