Where are you located? I’m in Seattle, WA and have a 2004 PVP chassis with single cylinder CR250R. It was a winning ICE package back in 2008 and 2010, but needs some attention as it hasn’t been used in several years. I haven’t officially listed it for sale, but if you are interested PM me and we can work out details.
I also have two Anderson karts that would easily accommodate either a 450 single or 250 twin. Either one can be sold as complete roller, just bolt on engine and go! Both karts are currently participating in AKRA and WKA events and are located in Ohio.