tonight the block was soft soldered into place and the skeg replaced, motor tests done, no noticeable increase in current draw - still at 1.7A as before I fitted the support, when installing the prop shaft and associated parts, keeping the current draw low means everything is well aligned.
You can see the skeg has been slightly angled down to accommodate the 35mm prop, this is 5mm bigger than model #1. I actually have 40.5mm clearance now - not quite enough to go up to a 40mm prop. next the rudder will need to be fitted.