Your link gives the option of a white primer.
Go with the white primer.
Spray primer over the repairs till the repair is no longer visible and it is all white(be it different shades of white) then sand and move on to your base coat.

Gray primer will be fine too, it will just take more coats of base coat to cover it up.

Don't use the dupli color primer in a can.
Auto shops have cheap spray primer that works well too.
Here I believe it is $13 for a can of transtar primer spray can.

Serf27 wrote:Your link gives the option of a white primer.
Go with the white primer.
Spray primer over the repairs till the repair is no longer visible and it is all white(be it different shades of white) then sand and move on to your base coat.

Gray primer will be fine too, it will just take more coats of base coat to cover it up.

Don't use the dupli color primer in a can.
Auto shops have cheap spray primer that works well too.
Here I believe it is $13 for a can of transtar primer spray can.

Thanks!

I did a couple more coat with the White Dupli-color primer, putting more paint at time. Seems to be covered pretty good now.

I am moving to 400 and 600 wet sand and then base coat.

I only have 2 cans of base and 2 cans of midcoat. I hope it's enough!

2 cans should be more than plenty if you are just painting that area of the bumper and blending it in.