So i'm halfway through fixing up an old road frame with modern day bits and have hit a snag.... There are no housing stops welded to the frame to bear the force of the cable on changing gear. I've realised I can solve this by simply running the housing all the way to the bottom bracket stops but i'm not sure whether that will cause a lot of extra friction or not? If anyone knows or has any alternative solutions then your advice would be greatly appreciated.

Assuming the bike had friction shifters on the downtube, you could get a pair of these:

https://harriscyclery.net/product/shi...osses-1737.htm

I can't get that link to work, but I assume it's for housing stops. You can also buy clamp-on stops that you can put anywhere along the tube. I've used them a few times, and they work fine. Cost about $12 last time.
Or you could just run the housing. With modern high quality housing, a couple of feet extra doesn't degrade shifting much

Yes, it's for the housing stops that mount neatly into the downtube shifter bosses. Here's another link.

https://www.amazon.com/Shimano-Shift-...1170036&sr=8-1

I have run housing the whole way using friction shifters and it worked without any problems. I have never tried it with index shifters though, so I can't speak to that.

Thanks mate i'll look into that.

^ The barrel adjuster on those will be an improvement over just running cable the whole way if you're using index shifting.