Might wanna consider a Crower 60243 or a Crane 283951. I think Cliff has posted some good numbers for 400's with that Crower cam.
https://www.crower.com/camshafts/pon...m-284-hdp.html
https://www.summitracing.com/parts/c...IaAusEEALw_wcB
A Howards 410051-14 might even work, since it has a 114° LSA, and 285/295 adv duration.
https://www.summitracing.com/parts/h...w/make/pontiac
No, I've never used any of these 3 cams. I ran an 041 clone/Rhoads lifters in almost everything. But it seems that when I recommend that, most can't stand the ticking sound the Rhoads lifters make.