No-one with any experience of really 'hot' cams would dream of using anything much hotter than a 276 in a road-going 1275. Torque is what is needed for a road car and one of the best cams is the MG Metro/Kent 266 (virtually identical).
A 310 might be fine for pulling 7800 rpm in top down the straight at Silverstone, but on the High Street it would be virtually useless and cause a lot of by-standers to laugh at an old car with all revs and no go.
Is that your opinion ?
I would rather say that it is experience from almost 60 years of working on Minis of all types.
My 1964 'S' will drive on the roads with a 286 and a SC CR gearbox together with a 3.9:1 FDR, but it is rather 'cammy' and on tarmac rally special stages/tests where I can keep the revs between about 5000 and 6600 rpm it is especially good. However, on a normal road drive, my 1990 Cooper with an MG Metro cam is just as quick and much smoother. But then I am not then looking for the fastest possible time over a given distance on narrow tarmac roads, although that is not to say that I drive it particularly gently.
Engine wear rate is also much lower with the MG Metro cam as it doesn't have to rev high all the time.