So yeah nah, I gave up trying to fit the 29s it was going to be garbage.
Buy 3 new bikes
First, a Raleigh pioneer which accepts the 29" no worries
May set this up as a single speed or 1x7 or 1x9 depending on what parts I dig out of my pile.
Would also make a legit tourer, have the original fork too but I gues the stack height was a bit low for the guy.
2nd I wend and bought a nice modern mountain bike. All clean and shiny
Then took the wheels off it
27.5" fits nicely with the mods I've don't to the rear, will still need to widen the forks a bit, but won't need to clearance the top of them.
Also there's disk brakes, so some brackets for them, and some gussets everywhere else
If anyone wants the remains of the other 2 bikes (a Canadian mixtie and a small melvern star complete less the wheels HMU)