I just put a 68 camaro 250 into my 59 GMC 100. I fabricated an engine stand mount that uses the 68 camaro motor mounts and also fabricated a crossmember mount for the rear trans mount. Being it is a GMc and I replaced a 270 I had ample room to move the engine forward or backwards. I could have used any v8 auto trans but I elected to keep the clutch and floor pedals. I was fortunate that my placement of the engine and trans allowed me to reuse the driveshaft even after replacing the dana spicer 45 (3.07) with a 67 12 bolt rear (3.73). I will post some pics.
Being the 270 had a taller deck required making sure my 250 fan blades were in near correct position on the radiator. You may not have this issue. I do recommend changing the valve seals in your 250 unless newly rebuilt.
Last edited by 42465967; 12/20/20197:26 PM. Reason: words