O would sugg3est the 390FE.
Why?
1) Is is affordable compared to pro built 351w
2) He will want an FE sometime down the road
3) It has the right look
4) They are easy to source
5) Take a running 390, new heads, H2O pump,
oil pump and pan, new intake and carb, it will produce 400/400+ easy and run on pump gas for ~$3500 to $4000
Last) He will want an FE sometime down the road