Which engine

[Eduardo]

My 1971 F-250 do not have an engine (originally a 360) was purchase as roller. The C6 transmission still in the truck. Economically what will be the best approach purchasing a remanufactured 390 and everything that goes with it, or a newer take out engine. Maybe, even a L6 300? Do the 300 bolt to the frame perches of the 360 ? Will the C6 attach to it? The engine bay is empty even the radiator is gone. It will be a daily driver. Thanks Edward.

[DuckRyder]

An FE C6 (FE being the family a 360 and 390 belong to) will only bolt to an FE.

My understanding is that you move the FE perches for a 300.

From a $ spend to get it running buying a running take out 360/390 from someone/somewhere will be the cheapest, but maybe not the easiest or fastest.

There such engines here in the classifieds from people who are converting from time to time...

[flyboy2610]

The #1 question to be answered is this: What do you plan to do with the truck? Is this going to be a work truck or a play-toy? A 360 will produce a lot of torque, but it does so down low in the power band. A 390 will give you more get up and go, but it's not as good a work engine as the 360.
It's like horses: You won't win the Kentucky Derby with a draft horse, but you won't pull stumps with a race horse.
How do you plan to use the truck?