no not in-line, between the high beam and ground
As for size, I'm not sure but the 'biggest' one that will work to quench it
Try 1K for starters - 1/4W (or better) is plenty as far as power rating goes at that size.
If you have to go below that, say 470 ohms, you would need at least 1/2W.
Alternative is to put a diode in-line (yes in line this time) with the feed to the high beams (one on each light) but the diode would have to be at least 5A rated.
That way the high beam signal forward biases the lamp but is reverse biased off the bleed-through.