GMdad Just a FYI - I used a 78 nova front clip in my '51 gmc. The 4200 is an easy install once the oil pan is mod'ed I reused the OEM frame mounts and made brackets with 3/16 plate and 2x3 box tubing. The trans cross-member can be reused.
Start to end 2 days of fab for the mounts would have a 4200 bolted in. $99 to Limequat to re-jig the PCM. The 78 has a common fuel tank fuel pickup neck upto early 90's fuel tanks so you could reuse a j/y pickup/in tank pump. The rest is plumbing.
Start to end 4 weekends and it would be running. A good running 4200 can be had for $500. All in I bet it could be done for $900.
Keep the OEM motor if you ever wanted to restore it. Bonus is no chassis mod's.
