I only came across this forum today,but I put a 1950 Model 7 Norton 500 engine into a Matchless CS frame. With a set of Norton P11 engine plates, it was a very straightforward thing,with almost no problems. Even the stock P11 head steady bolted right up to the 500 engine.

L.A.B. has kindly agreed to post a photo of my Matchless rolling chassis, I have also recently bought an oil tank off a G15, so I feel the project is racing ahead, although I still need lots of other parts. I intend to do the bike as a G15 based project and will probably order an alloy tank from The Tank Shop in Scotland. They have a very nice Matchless badged P11 tank on the web site.

Here's a pic of how mine looks so far:

That's going to be a classic looking old beast!

I have just received some G15 engine plates and various other bits and pieces bought on ebay and I'm very pleased to say that I loosely assembled a Commando bottom-end into the frame and it looks like it will bolt in with very minimal modification to one lower frame lug. Additionally one of my chums has recently purchased a G80 of the same age as my chassis so I can check the various cycle parts that I need by looking at and measuring his.

Practically done!