depends what era you want to run it, and what era the parts are from...... if you want to go pre 70 well it has to look pre 70 as does the motor and the mechanicals, if you want to do pre 75 as above but the rear disk is ok if it is a airheart, wessel etc the old 20 cent piece disk pad type, front could be same but your less inclined to get greif if you stick with a drum ( altho in TT they did run the airhearts on the front pre 75 in Dt)
If you have more modern stuff on it then you can go pre 78 and so on. so the short answer is absolutely. the only descision is what perid do you want to represent, and what bits are you willing to change, and youll find you spot on the entry form.