I'd try and strike a deal with HTH or Toe-knee here, since you are in the UK. A Framus design(as well as a few others) can be built on a Soldano SLO board so I can't see any issue with sourcing and you'd have the ability to have them customize the circuitry to your needs post-build or even spitball some changes pre-build with your input. Can't really beat that, IMO. Now if you were in the US where 5150s sell used for $5-600 all day, I'd suggest otherwise depending on your cash/quality needs.