My bumpers are straight, but are going to need to be re-chromed...especially the rear which has a break in the chrome. Someone either put a later bumper on the front (I have a '71 BTW) or they had the front drilled and added the bumperettes. I do not like them and want to remove them. So the question is do I simply have the shop fill the holes prior to rechroming the bumper, or do I look for a replacement and just sell/trade the one I have? What's the market like for a later year bumpers? I don't want to ruin something that someone else might be able to use.

you can weld up the holes...before you re-chrome.

I would agree. Simply weld the holes grind flat and then have rechromed. One can tell the guard bumpers from the non guard bumpers as the guard bumpers had two extra reinforcements behind the guards for absorbent rubber blocks to fit. Non bumper guard bumpers are clean except for the mounting plates on each end.

I'd agree with closing the holes with welding (make sure they use good metal). Just as importantly, make certain they grind/sand them down to flush. if you don't use good metal & grind it down properly, they will be more than noticeable.

For my money, I'd sooner look for a proper bumper, even if it must be redone. I think that 5 years down the road you'd be better off.

But....MHO

Word of caution. Yes I am sure you can fill and grind the holes yourself. I would recommend that you let the rechroming shop do the fill and grind.
The shop where I have all of my rechrioming done, does all the filling and grinding, that way I do not get dinged an extra charge because they have to redo it. I know because I asked them this very question. " Can I fill them myself" "Sure, but we will charge you to redo them,"
CCLINCHROMEBAWLS