What year truck are you working with? You'll need a different starter, along with a different ignition switch and some minor rewiring. Stomp start was not an option on the V-8's. Depending on the year, you'll need one of a couple of different styles of front motor mounts. I believe the radiator can be re-used, but there might be some problems with hose routing. You'll also need to buy or build a fan shroud because of the distance from the radiator to the engine. IM me or send an email- - - -I might have some of the swap parts you'll need from my 59 Burb that's getting a Cadillac 500 transplant and your 261 is good horsetrading material, even with a bad crankshaft.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!