It's the hidden costs that get you, they all add up
Larger fuel lines & pump, surge tank, RWD conversion of the motor (cut n shut plenum e.t.c), custom mounts, T50 box, custom tailshaft, Larger radiator , Thermofan and then there is the wire up cost, the engineer cert
All those things your looking at $2500-$3000 and if you notice i haven't included the actual engine yet or a computer so slap that on top and your up to probably $4000-$4500
And remember the only thing pro listed is the wiring & engineer so for that amount you would still need to do the actual install of every thing else yourself
The reason i know is i'm going through the exact same transplant ATM except i'm also adding a turbo so mine's going to cost more
Hidden costs are the killer of every engine conversion, The engine itself is the cheap part :P