All the available repro 69-70 front bumper rubber shields have a mildly rough texture as they are made from fiber
impregnated stock.
The rubber shields on my original/never restored/never in an accident 69 GT500 are smooth.
The rubber has gotten pretty hard with age and there is some breakage but it is nothing like the rough stuff being sold.
There is a rubber supplier in NYC on Canal Street (Canal Rubber) with a mind boggling variety of rubber sheet stock.
My last time at Canal Rubber I scored some pretty close to original p/s hose sponge rubber covering.
Some called it "driver grade" not concours but it was a very good match to my original.
I no longer live in NYC (now in PA) but will have to make the trip to see if I can score something that matches my original.
Personally I don't care who says "that is not correct" or "as originally supplied by Ford" I try to get as close as possible to what is original on my car.
TonyS