how much?
 

i have the oppertunity to get a 74 f250 w/ a 360 and a blown tranny for 200.00 the engine was rebuilt but very seldom started in the last couple years due to the large consumption of gas and a 2 hr commute to and from work! should i buy it pull the motor scrap the rest, rebuild it get a new tranny and put it in my 92 GT?
how much work and modification will this need?

Thats is an easy swap, pretty straight forward and simple.

You know what they say. "There is no replacement for displacement."