Will help all i can so just post away. The old crank maybe ok, is the bigend of the crank damaged where the conrod has broken? can you just swop the conrod and bearing shell? ive got loads of shells if ya need them. Ive had an idea and think you can use the oil feeds that are already in the gk73 casing ( got plugs in) they feed the oil cooler on previous model and should feed ok but are 14x1.25mm thread, will save the work of opening the feed on the bottom of the sump.

Is it gonna be easyer to get a gk73a/gk75 head? i have access to a load of gsxr 400 (gk73a) parts (carbs, cdi)

Mechanically it would be loads easier as everything is interchangable but im not sure about the electrics as the VC has an extra relay that works with the oil valve on the head and the cam sensors, works by the cam sensor giving open or closed circuit when its turned by the inlet cam as the cdi sends 12V to the oil valve or maybe not sending 12V and this then turns a rack and gear that turns the variable cam followers using oil pressure, so im not sure if the cdi will be happy with no VC running. You could go with standard wireing and cdi tho. If the cam drive sproket in the centre of the crank is the same on both motors it is simply a straight swop so this is the main thing to find out, like i said they got differnt chains bit i dont know if they run on the same sprokets.
Chris.

Had time to dig about in the parts No. list and the cam chains are different but cranks and cam sprokets carry same part No. so am thinking apart from the cam chain the rest should swop over.

ok mate i will have a look and post pics when i get a chance

i think it will be easier to sell what i have and buy a complete engine.
So, i have a gk73a (gsxr) bottom end, barrels and pistons £100 and a complete head for a gk7aa (VCbandit) £75
I also have an oil pump, gear box parts, complete clutch, one piston and con rod. All from a gk7aa, Offers