Just noticed you're local, could be handy!

Do you drive? I'm in the centre of Manc, if it comes to it I could give you a hand getting sorted. Cost you a beer or two mind
Had a proper look at the pics now (nice wheels) and I reckon you're in the classic 'is it worth upgrading?' situation. What you've got is a really nice retro project, but that's not really what you're after I don't think. You might find someone on here keen to take it on though...
I think, given the inch threaded steerer & non-sus geometry etc that by trying to do it up as a day to day ride (as oppose to a faithful retro) you may just be on a hiding to nothing, certainly money wise.
If you were to split & sell it I'm guessing you'd raise around £70 (anyone have any thoughts on this?) mostly from the frame & wheels, throw another £50-£100 onto that and you could pick up something nice on here or ebay that's modern enough to be easily adaptable as your riding progresses. I just bought a basic but really sound Schwinn Mesa off Charlieboy for about a ton & I'd be totally happy to ride it anywhere, it's got decent brakes and will take any (appropriate) fork of the last ten-fifteen years.
Really hard to decide, as your frame is lovely, but I think doing anything that moves away from it's original fast, rigid XC incarnation may well just spoil it.
Hmm, less helpful?
You could sort out stem, headset, and a bike's worth of V-brakes & levers (so you don't need a cable hanger) for £40 I'd think, friendly shop may fit the headset for nowt if you're a regular, then add forks as you'd like. My concern is that your current forks look really short, so even a 63mm travel fork might be enough to ruin the handling.
It's a tight spot! Realise I'm not saying what you'd like to hear as well, not to mention that I'm likely to be hung, drawn, quartered & (worse) banned from RB! :shock:
But if it were me and it was going to cost £100-£150, I'd be looking for a decent, lightish hardtail to get me started & either continue to run the Kona rigid as a commuter/long term project (18lb singlespeed...?

) or sell it on here as a project/frame & parts to get some cash back.
I'm expecting some possibly very different opinions to arrive very quickly now though!
Good news is you basically can't lose from your current position, bankruptcy aside... :roll: