It'll be 48 for sure - first Iron Fist team-up, Byrne art, low-selling point of the series (I missed that one growing up, and only caught the Byrne art by 49), Daughters of the Dragon appearance, IF vs. PM fight cover, etc.
50 is a possibility, as it's the first official title and it's got Byrne art, but I doubt it.
And as for 54, huh? The first time they pluralized Hero for Hire? That's sucker bait for the feebs and dweebs to waste money on. Buy PM 48 if you really think the team-up is going to heat up in back issues. But 54?
Isn't 50 the first team up? I thought they fought each other in 48?