Hi all just won this -> http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 774wt_1141 The mounting points look very similar to my 400 does anyone reckon I'll have a great deal of difficulty installing it?

In Short no it wont fit, the engine is bigger, you could get it to fit if your good with a welder.
But you also need SRAD Clocks, Loom, Carb's, to make up a airbox to fit your frame, CDI etc.

What was wrong with your engine that it needed replacing?

seen a GSXR 750 M motor in a 400 frame before. but it was the later model slingshot frame. had to modify the tank to clear the carbs though. dont know if this will fit but worth a shot =)