Not if his rpms are 500 faster while the speed is ten mph slower.

3:90 with the TH350 should give him 60mph fairly easily. 4:11 may not.

But he does need to make sure the engine is properly tuned and running right first. Then hunt the transmission problems if there is one. If the engine is running right, then he has a gearing problem.

I think if the transmission were not shifting into high gear his rpms would be much higher at 50mph than they are now. Course I could be all wet too. LOL