Did he strip boat and reinforce the hull with frames?
No, not on either boat for the sake of the rig. (He did put in collision bulkheads and extra buoyancy.)
Is there a sail plan?, rigging plan?
Roger used the "Hasler-McLeod" sailplan for both Mingmings. In the case of Mingming2 he used a unique "hybrid hinge" method to get some camber in the sail. There's some info in his videos.
info on centre of effect and mast step?
I expect Roger himself might be the best person to ask for measurements for the Achilles. You can find him in the membership directory.
an all in one build manual? I thought asking may save some time?
"Practical Junk Rig" remains an excellent book for details, especially of the Hasler-McLeod rig. I'm not an expert on conversions, so I'll leave that to others. However, if you want to come and take a look at my Coromandel, do get in touch. She's around the Solent this summer. She has a traditional Hasler-McLeod sailplan, straight out of the book. That doesn't mean you should just copy it, but you can certainly learn something by looking at it!
Richard (called, but not yet chosen)