Right this will be the start of my project thread for my 340, as it stands I have hit a huge brick wall during the engine conversion, the engine is out of a Renault 21 turbo and looks like the engine mounts will line up etc, however the bell housing is another story, has anyone done this conversion or heard of someone who has that can point me in the direction of what to do as I am having real thoughts about selling up and buying a jap car

According to this:

"Discontinued"
The F2x in an 8-valve SOHC with double-barrel carburetor
Applications:
F2N 1.7 L (1,721 cc (105 cu in), B x S: 81.0 by 83.5 millimetres (3.19 in × 3.29 in).
1985–1989 Renault R11
1985–1989 Renault R9
1985–1995 Renault R21
1988–1996 Renault R19
–1997 Renault Clio
1985– Renault R5 Super 5
F2R 2.0 L (1,965 cc (120 cu in)).
1985–1993 Renault R21 (No official Renault references known, some says 90 HP, others 102 HP}

The 5 and 21 shared the same engine, so look into the renault 5 conversions which has been done a few times and it should help with the conversion With regards to the bellhousing, usually to fit the renault engines in the volvos it requires the 1.7 bellhousing and mix n match of the clutches out two, something like the 1.7 clutch with the renault centre plate i believe. Hope this helps

I've often wondered if this conversion was possible as my dads old 21 Turbo was a proper road rocket.

I hope you get it sorted and don't give up on the project.

That appears to be an F-series engine rather than a C-series, I'd be very surprised if it bolted up to a 1.4 bellhousing! The 21 was front wheel drive with a longitudinally mounted engine and a UN1 transaxle type gearbox. Take a picture of the clutch end of the engine mate, we'll have a look. If that's a 2.0 MPi turbo lump you have there it'll put out 175hp so it's worth at least looking into making it fit.
And of course if it won't go I'm sure it'll be worth a few quid, rare items these days.

I believe the R21 turbo used a J-series engine, from a totally different family. It may still bolt up, of course, but I'd not hold your breath. The turbo lump from a 400-series Volvo will fit (that's an F-series) with suitable work (including flipping the inlet manifold), or you're back to the usual F7P/R options.

cheers

James