Hi Softfeet, don't worry about the length of your post, you should see some of Paul L's...
I run tubed tyres on MGB 14" wires (not tubeless wheels), and I buy my reinforced tubes from a local (to me) tyre supplier in King's Lynn.
I was quite surprised that a modern tyre fitter still stocks tubes in just about every size, but they told me that there's a big market for them among Stock Car racers (there's a race track in King's Lynn).
The stock car racers fit tubes to tubeless tyres on their race cars because the tube keeps the tyre inflated and stops it coming off the rim under the massive side impact loads the wheels get during their 'contact' sport.
It's true that tubes are vulnerable to punctures from any debris that's in the tyre or stuck to the inside of the wheel when they're fitted, and in the last four years I've had two slow punctured tubes, both on the same wheel.
That wheel's got a bit of rust on the inside ends of a few spokes and the rust occasionally breaks free, wriggles out from under the big rubber band that covers the ends of the spokes (essential fitment with tubes), and slowly but surely rubs a tiny hole in the tube. This leaves me with not a lot of ground clearance (need to invest in a bag jack) but otherwise isn't too bothersome -
Both times the tyre has deflated very slowly, like over the course of a week, and, touch wood, I haven't suffered any blowouts, which I have on one occasion with a tubeless tyre on a mini at motorway speed back in the 80's.
Luckily it was an empty stretch of the M4 (is there any such thing these days?) and although it took me about half a mile and all three lanes plus the hard shoulder to finally get the car back under control I didn't actually hit anything, or I'd be typing this from the 'other side'...
There are pros and cons for both, so tubes or tubeless? You pays your money, you takes your choice.
As for the size you're going for, is there any reason you want to keep the tyres that narrow and with a 70 series profile? I ask because you might find that they look a bit small, depending on the car they're fitted to and the clearance you have around them.
I started out by fitting 175/70/14's to my Spyder, but they looked a bit lost in the arches compared to the 175/80/14's fitted to Phil and Barry's cars, so I swapped to that size (175 is the widest tyre you can safely fit to a 4.5" rim, btw) -
My car just looked too low to me in this shot -
175/80/14 on the left, 175/70/14 on the right, and it's surprising how much difference there is 'in the flesh' -
Here's my car on the 70 profiles -
...and on the 80 profiles -
Much better, and I'm sure it's the fat tyres rather than the fat driver that attract attention at shows...
So, hopefully that's given you a few things to think about, but I'm intrigued now, what car are you building? Pictures please...