The 200,000 increase was after bills. I did a bit of fiddling with it all and found that the decrease in upkeep was marginally smaller than the increase that I'd get from silver or uranium (pre-nuclear weapons)
Just an example from an old spreadsheet I had with my nations stats in it.
Bills Amount Upkeep per unit Total
Infrastructure 4999.99 $336.09 $1,680,446.64
Without lumber that would be roughly ($336.09*1.08)
Bills Amount Upkeep per unit Total
Infrastructure 4999.99 $362.98 $1,814,882.37
For a difference of $134,435.73
With 52,786 citizens, that means any resource that gives me a happiness bonus of about $4.08 before multipliers would give me an increased benefit over having lumber.
Silver gives a bonus of $6
Uranium (Without nuclear weapons) gives a bonus of $5.5
Wine (Which I would've got but marble was one of my native resources) would give $6
Hopefully my math wasn't to off, I whipped this up pretty quick but I don't think I overlooked anything.