I had a 305 in my '38 that had 99,000+ miles when I bought it for $500.00 and I replaced the timing chain [censored]. and a couple of gaskets and never regretted it . I put another 140,000 miles on it and it gave me 20-22mpg without an overdrive (2v carb) ! It should still run but I'm completely redoig my truck so a fresher motor is in it now . The 700r4 will bolt right up to both the 305 and 350 , externally the motors are the same so have at it - Motor mounts and everyhing .