[SAJ]

I have fitted the centre horseshoe mount with Mitchell OD. I had to do lots of machining on the bracket and slot the Mitchell gearchange mount on its centre hole, mount one of its bolts and rotate it on this bolt into place under the floater motor bracket with the centre hole bolt loose enough to get the Mitchell bracket under it. Then all could be tightened in place.
My F/M horseshoe bracket was aluminium and I removed a lot of material from the top to get the Mitchell bracket fitted. But it has still proven strong enough for 20000miles of hard work.
It originally broke off at vertical bolts on both sides before I fitted the Mitchell and I had terrible clutch chatter until I welded, re-threaded and secured it again , as Synchro found.
A cast iron F/M centre mount would be preferable but harder to machine down (bevel off to about half original width if I remember correctly and then modify the F/M snubber plate a bit, using cap screws to secure it to the horseshoe part). An angle grinder would work, but I may mill it. Hacksaw and file may be possible for those deprived of workshop tools.
This is all for a RHD Roadster. LHD Mitchell change lever bracket is different and may make things easier.
I am about to change my Wife's Tudor to Floaters, because I have a lot of pulsing vibes on over run with higher compression and lightened flywheel.
I do not have this pulsing in the Roadster. Both engines are fully balanced. I weight-matched pistons, big ends, small ends etc myself , but I did not see the balancing results on crank, flywheel etc.(the graphs).They had lots of new drillings and pressure plate was marked for indexing by the balancer, so I assume It was well done - I cost quite a bit!
It will be interesting to see if F/M s improve the pulsing when cruising downhill on trailing throttle.
SAJ IN NZ