Back in the 70's I tooled around on 36 / 36, the older rear 40 having been superceeded.
I could use my Fiamme Road 36/36 sprints and tubs as a general replacement for the 27X1/14 rims/ tyres. I generally road raced on 36/36 too.
For TT's I'd sometimes swap for a 32 front if I was riding there or rarely used a 28.
Old style tub rims are pretty bendable, pick one up and you can bend and twist it...........it's basically the spokes keeping it together.
As time progressed the rims became stiffer / heavier which allowed for less spokes but more aero.
The generally accepted "strongest" tub rims are SSC's but NOS they cost as much as a bike LOL
Shaun