I've run rear coilovers with front torsion bars on my '73 for the last eight years without issue. There was minimal bracing done in the rear towers and all is strong. This is mostly a DE car, though built for vintage racing, it does not see the stress of full season track car. I chose to go this route and avoid the rear torsion bar hassle...my car builder had no problem sourcing parts, mostly from TRG.
