In the UK the paintable front bumper is nearly twice the price of the standard one. I hit a deer in my old 98 4.6 Ltd Edition last Christmas and bought a standard bumper which the paint shop rubbed down and sprayed to match the car - exellent finish and not much rubbing down. i think they used a spray filler on the bumper first.
Any, ANY bumper can be painted to match. It all depends on the shops ability and experience. You made no mention of looking to cover "grainy texture". If you want glass smooth finish, start hunting and befriending local shops.
By the time they had rubbed my new standard bumper down and sprayed it Epsom Green it was 'glassy smooth' and no sign of any grain. The graining is not that deep and by using a filler primer suitable for use on plastics the finish was perfect.
Front end parts for Rovers are very hard to find. For all the claims of great braking systems, the P38 seems to run into things more than it gets hit from the side or behind. Spend some time on car-parts.com searching scrapyards and you'll see what I mean.
You can now buy an entire P38 in running condition for less than $3000. It's beginning to hit the point that no one will be fixing these cars so the demand for parts will fall and the number of them in scrap yards will fall also. For folks that really want to keep one running purchasing a whole donor vehicle is beginning to look attractive.
So then what is the difference between part #DPB104600LYT, which shows up as the needed part for the VIN on my 2002 Range Rover and costs a whopping $~900
and the much cheaper bumper ($~550) offered by many online vendors #DPB103830G.
They look the same and the latter is noted as suitable for all 95-02 Rovers on Atlantic British. Is one ready for paint and the other not? Then again that wouldn't make too much sense, as my 02 came from the factory with a somewhat textured bumper. It was certainly not a glossy body color. I had to have that done custom after the fact.