Just to update, I went the lazy 'buy stuff new' approach. I bought a set of 25mm bearings from ebay (£6), a stainless steel 25mm rod for £50 and some steel box section. Welded it together to make a frame, mounted the 25mm bearings into 23m holes and the pole sits on top of the bearings and rotates very nicely with minimal friction. Both myself and a friend could stand on the steel bar on the bearings and it would rotate and the bearings didn't pop out.
I cut the 3m stainless steel rod to make 2.5m and have a nice 50cm heavy 'dispatching' pipe for fishing...
I don't know what the health and safety rules are on roasting kits, but assuming the meat only touches stainless steel it shouldn't be a problem and I can probably get away with doing a few roasts selling to the public at scout events. Quite often we're asked to do burgers at events because 'hog roasts are too expensive' (ie they actually charge the organisers to turn up!). I've bought a few stainless steel U brackets and spikes which have collars to fit a 25mm stainless pole. I can't weld that sort of thing (infact my welding is pretty bad as it is!)
Got two halves of a metal barrel to use for containing the charcoal.
Local reCycling have offered me the sprockets to make gears & will be going to a scrappy to get a windscreen wiper motor.
70lb pig for £168 delivered (I think that's fairly reasonable).
Where's your invite? Probably lost in the post