Its a good path: one i have done myself in the past, but then moved and changed jobs so that I have a lot more open flat then huge hills on my commute so throwing my fully geared bike on my shoulder is a small price to pay for the speed and climbing capabilities gears give me.

Also Scotland makes sense: few in the US would be thinking to mod a Holdsworth as they are relatively rare (and beautiful) - and why not just mod a Schwinn?

As others I'd keep the fork as unless you spend serious money on a CF fork, its not actually that much of a weight gain. The weight vs price is huge on CF forks: cheap ones are heavy, expensive ones are light- if you have the cash, go for it and get something ridiculous. but if you have not, you wont gain much if anything over the original.

bars and cranks- yes: why not. seatpost and saddle, sure. then its all about the wheels. I have not found a set of wheels that are light, strong, and smooth for less than $300 USD. so that is a big consideration but makes more difference for the ride than anything else.