timing covers and distributers interchange between gmc engines of the same vintage... example 228, 248, 270 and 302. I think there may be some interchange between the earlier 216 chevy engines as well.
There are plenty of parts that are still available for the 235 including pistons, bearings, camshafts, timing gears, intake manifolds, headears, dress-up items, water pumps, clutches, etc.