[Ron Ramirez]

One has to take the Philco part numbers of the original resistors used in model 20, and compare that with known data from vintage Philco paper, such as old parts catalogs.

Here are the resistors used in Model 20, excluding the large multi-section "B-C" resistor

(12) - 50K - Part No. 4237 - 1W
(15) - 250K - Part No. 3768 - 1W
(17), (20) - 500K - Part No. 3769 - 1W
(18) 100K - Part No. 3767 - 1W

So, all those small resistors under a model 20 chassis were originally 1 watt each.

I agree, most if not all of them are probably overkill, wattage-wise. But why take a chance? Just replace them with new 1 watt resistors. Your radio will be happy, and so will you.