Not sure I'd call a Howa a Remy clone, besides it's far superior out of the box IMHO.
There's a chap on Guntrader selling a Remy action for £405 as part of a custom build, just search for a bolt action rifle with 308 bolt face. You may also find a second hand Remy there, it doesn't need to be 308 if you're rebarrelling, it could be 243, 22-250 or at a push you could probably get a 223 and have the bolt face machined out and extractor changed.
You could save a certain amount of bother and just get a proper custom action, South Yorkshire Shooting Supplies are supposed to getting some Lawton actions. I was toying with the idea of getting a Surgeon action earlier in the year, I thought I'd hold out for a cheaper Lawton, that was before the pound took a nose dive.