questions about making a hybrid rocket.

I've searched the forum with no luck, Black front rocket rf lower is listed as 19" same for blue/gray. can they blue/gray lower be a replacement, yes im aware of having to make spacers for the heim ends instead of the bushing. Also what about swapping in blue/gray drop spindles to add ground clearance? Helping get someone started into racing and want to make their car the best it can be the easiest and if they can run blue/gray components then I can help them with spares. Thanks

I have never actually compared the lowers but i don't think it's a great idea to mix and match. I've not seen much success from running the raised spindals. If he's a beginner i would just concentrate on making the car right. No binds straight parts etc... once he gets going you could play with altering front end components to see if it's better or worse