I am seriously considering picking up this truck!

It is a 360 gasser / auto / 4.10 rear 2WD, supposedly 60K original miles. Starts and runs good, haven't driven it but it supposedly drives out OK.

There is a little rust under the OEM rubber floormat (which is wet, so there's water coming in somewhere) but absolutely no rust through in the floors or rockers. Some small, easily repaired rust holes near the floor on the interior of the pillars between the front and rear doors. No rust in doors. Some small rust holes in the tailgate and right front fender. Heat / AC control is broken. Seats would clean up fine.

My plan would be to eventually convert to a shortbed with a 12-valve Cummins/ stick.

How much is TOO much to pay for it?