I agree with
Birdieman mix matching parts isn't a sin but still doesn't make for a replica.
STATING THE OBVIOUS
If you're going to make a replica, stay 100% with historically correct parts.
I like the STEEDA and SALEEN stuff, but I would say it depends on what you want the finished producted to look like. A SALEEN wannabe or a STEEDA wannabe or the best of both

.
Both make great products. I wouldn't say either make the best - but both make good systems.
IMHO:
Body kits - depends on what you like
Suspension- GRIGGs / Max Motorsports
Exhaust - depends on goal/likes
Motor/drivetrain - not going there