Which engine would you recommend?

[freshtiva]

Are there identifying marks on the B6 that would differentiate it from the B3?

"Mazda" on the valve cover might give it away as well as the intake that doesnt go over the valve cover on the 1990 + motors.

[Damkid]

^^He could just use the 88-89 B6 and it should look the same as a B3

[eurotiva]

^^ ilove that car. Some of the b6 valve covers are plain, just like the festy one. And the twin cam has the intake over the valve cover but that would be more obvious.