1969 250 I6 to 1980 350 swap..need info

[mr_gm87]

Hello i have a 69 gmc 1/2ton with the 250 I6 and 3 on the tree in it and was wondering if i would be able to put a 350 from a 1980 gmc 1/2ton in it. Just wondering if i can get 350 mounts from a newer truck (71,72) and trottle cable and if they would work with the 1980 350. also if there would be any modification i would have to do to go from the 250 I6 to a 350 . and also if i could maybe switch to the 1980 auto tranny as the truck also has a rebuilt th400 in it . but am ok keeping the 3 on the tree if have to . I am getting rid of the 250 as its now knocking and using oil, was going to rebuild it, but decided to switch to a 350 as i would like to drive the truck year round daily and pull my trailer with it (just a smaller single axel one). and found out that people where right that the 250 is quite thristy lol