what do you guys think

[68GMC454]

ok i called a guy i know that has a jukyard full of old stuff..i have delt with him in the past and i trust him..but anyway i called over there looking for a straight 6..he said he has a 250 that he just got in with and 55 chevy truck..but he said the guy rebuikt the motor, and it is all new and ready to go..said he would take 350.00 for it with every thing i need to put it in my 68.. so tommrow i go look at it and make a payment arrangments for it. for a new rebuilt motor, does this sound like a good deal..i gave 300 4 yrs ago for a low milage 283 from him.. it is garenteed to not knock or smoke..