HP limit on stock 96 explorer rods??

Should be fine. Figure the car to make like 270rwhp before the nitrous. And if you use a 150 shot, Somewhere around 375-400rwhp.

Are the Y heads stock?
Y head and B cam combo isn't all that potent. And taking a 302 and making it into a 306 doesn't produce all that much power either.

270rwhp, may be a bit low, but still i wouldn't expect too much more. If you get more be happy.

Don't apologize.
Ask around as you should. But there have been plenty of cars here with y heads. And i had a set last year. Spent hours reseaching (after purchasing them, but before i put them on the car) The exhaust side is seriously lacking flow.
X cam isn't all that great for them either.
Those heads need a custom cam since they are so intake biased. .542 on the lift, and the heads flow 134@.500. Believe it or not, that's less than a P head on the exhaust.
Figure some guys here are having trouble getting into the 280's with X heads, and they are far superior to the y's.
Now if you were to have the heads milled, considering i think they were what 68cc or 64cc? Have them valve jobbed, bowls cleaned up, you are talking a whole different world. I'd say in that form you could get much closer to 300rwhp.
I had mine done up by the machine shop, the factory valve job was a mess, and one of the valves was getting hung up, and this is on a NIB set.