I do not have enough points to comment, so writing this answer:

Is this a kind of homework assignment?

According to your output, it looks like your code assigns/selects feasible combinations only once.

For example, the combination 1x 60’ + 22x 70’ is used in product #28, but could be applied more often as you mentioned.

Another keyword you may want to look up: backtracking

… and yes, there is a feasible solution with 60 products.