That's an incredibly generous offer of him, I would probably charge someone twice that to build a ceriatone kit. I bought and built the Hiwatt one and I would 100% do another, wish I never got rid of the one i built. That amp was amazing. They have really decent quality parts, and the DR103 I got was literally indistinguishable from a healthy vintage one.
Just based on the type of tones that you like, I think the dumbles would be up your alley, but I would wanna try some brownface era fenders and a HPTT as well. Both of those styles of amp absolutely kill for blues tones.