3 can as well as 2.
I am using using 2 repair and use 2 less supports than the suggested, and have a shitload of good repair rate.
If you don't want to scratch much your head.
3 repairs + 7 engineers.
2 repairs+ 8 engineers.
The only crew that should be Ellite is Repair. Even roll engineers will be better than Ellite Engineers at high lvl.
If you're new and don't want to be perfectionist.
10/10/11 (rep/res/engie) are perfectly acceptable, solid crew, and is damn good. They are very very reasy to roll.
Do me a favour, just don't ever class and use restore man on your BB.