There's drawing from a Lister SOM booklet that shows an exhaust system that could be excellent.
Also, it looks like it would be cheap and easy to accomplish.

Jordan

I'll keep you all posted Bob, though I'm proceeding at a glacial pace.

Jordan

https://www.ebay.com.au/itm/SPB-B-section-V-Belt-Pulley-w-taper-lock-suit-Any-standard-Bore-size-1-2-groove/233027040831?hash=item36417e763f:m:mnaeeHAqBLKIJ72A7jzd2wg

I ended up getting this for $83.37 inc postage to Sydney (free for east coast metro addresses).

i also need a 3kw generator to go with it.

I thought so too, until someone pointed out that I could use a larger output generator (which might be easier to find).
It will produce as much kW as the engine can cope with supplying, then no more.
I hope that's right, because I got an 8 HP alternator.

Don't panic, folks. There needs to be a white line on the alternator pulley for my digital tacho anyway.
I also have a frequency meter, which will look in keeping with the old genset.

I heard a suggestion for fine-setting of engine speed to obtain the required Hertz.

Assuming pulleys of theoretically near-correct ratio are installed on engine and alternator shafts:
Paint a white line on the alternator pulley, so that with a lamp shining (powered from grid, on a house circuit for example) the line will appear stationery when correct speed is achieved.
It's the same principle that was often seen on hi-fi record player turntables.
Has anyone else heard of this method?

For those interested, here's the main bits of the puller I made to remove the stubborn pulley.

What country?