Dodge viper + Ferrari 456

Im new to this and am only young so bear with me. I am currently modifying a bburago dodge viper with chrome wheels nos tvs everywhere side opening bonnet everything is smoothed there is a trailer which is the rear end of a viper and i am wondering wether to do a 6 wheel conversion as i now have a front and as the chassis is simple two cuts and it would be done.
The ferrari is extremer with a 1/16th drag engine beasty rollcage nos extinguishers modified suspension to accomadate the massive supercharged engine massive spoiler wheelie bars drag slicks at the back so serious arch modification is needed and hopefully a parachute.
Both are 1/18 and were picked up for a few pounds any suggestions would be grateful thaks $coobz