I have looked at this many times, but concentrating on collectable premium passenger GMH stuff. Essentially HK-HQ 1837 or HQ XW8, XU1 or L34. Maybe also dabbling in next level down so HK to HZ GTS sedan and coupe, SLR5000 and GTR.

But always been not worth the effort unless on the premium cars, but it simply costs too much. For example, a restorable HK 1837 (GTS327) without its engine is worth $50k. By the time you buy everything and complete it the cost would be $100k or more. You'd be lucky to sell one for more than $110k without its original engine and the supply of such cars to restore just isn't there anymore to be sustainable. When you get into the lesser stuff like SLR5000 the numbers stack up even less. Brad Hanrahan couldn't sell his beatifully restored and unique black LH SLR5000 for $60k and I bet the same car needing resto would fetch close to $30k, same deal with a restored Sandman has to be pretty special to fetch over $25k yet people think they are worth over $10k as a rusty restorer. The $ just don't stack up. You can buy a beatifully restored big block Camaro with all original driveline for $45k, or even a 1970 Z28 for $30's.

The only way I reckon you could do it would be as a non profit Charity or sheltered workshop where the cars were restored by either young people or disabled people under the guidance of retired or otherwise unemployed tradesman, where the people doing the work gain skills and maybe a trade out of it. Would be a worthwhile thing but you'd want to have won the lottery to set yourself up so you didn't have to work and simply did it for fun and for the benefit of those involved.