any ideas for a 406 sbc build?

Built a few 400's in the past. Use flat top pistons for pump gas, it will keep it in the 9.5-10.0 range depending on the heads you use. What ever head you do use make sure it has the steam holes drilled.
Cam can be whatever you want, I would use around .500 lift max for a street car. You will likely need a higher stall torque converter also.

I have built a few. The last one was .030 flat tops w/4valve releif, 461 casting camel humps with the factory 2.02/1.6 valve rebuilt with stainless valves bronze guides and hardened seats, and a home port job. Cam was a custom ground one that i had done .483 lift and 232 duration @ .050 with a 1.5 rocker, a edelbrock performer rpm int, and a holley 3310 750 vac secondary.
It dynoed at 452hp and 525lbft and was very streetable. I will try to find the dyno sheets if needed for rpm ranges etc. It worked well with a th350 and 2500 stall with 3.23 gears in my 80 cutlass then went into my 85 s10 blazer with 4.10's and worked even better
Traction was a bit of an issue though.
I would alter these specs a bit next time and use a comp xe274 or similar (i've had good luck with it) and vortec or aftermarket heads. The xe274 has a broader power curve and will work well even with a 2200 stall.

I just pulled a 406 from my 84 monte. Its got some 4 valve relief flat tops with a set of arrow reman heads with 2.02/1.6 valves with the xe274, an edelbrock eps intake and an edelbrock carb. I dont have any dyno numbers but its a very strong motor. When it finds a new home (girlfriends 87 cutlass) I am going with either vortecs or some aluminum heads. The monte had a 200-4r and 3.73 rear and made a really fun ride.

They do make monster torque, the biggest downfall was even the peak hp comes in at a low rpm with the long stroke. My blazer with a 26" tire and 4.10's was almost out of rpm in drive on the 1/4mi going through the traps.

10:1 d-dish pistons (hyper or forged AL) 5140 forged rods (they're cheap but strong), plasma-moly rings, vortec bowtie heads with 185-195 runners, Comp Cams XR282 cam (or equivalent), performer RPM airgap intake with q-jet or ram-jet EFI, and 1 3/4 tube headers
when i plug it into camquest (with stock level vortechs) i get 477 horse and 500tq. you'd probably break 500hp with the bowties. you'll want about a 2600 stall and a 8.5in or better rear. this can easily been done on a built 200-4r with 3.42 gears