10's on $5,000 ?

It’s unlikely the hp/ci will change much with what the budget will facilitate for mods........ so using a 400 instead of a comparable 440 will result in roughly a 10% reduction of hp.
However....... it’s easier with these budget builds to get beyond the 1ft-lb/ci than it is hp/ci.
Meaning the difference in tq will be a bit bigger than the difference in hp.

Take a typical 500hp/520tq 440.
Scale it down to 400 cubes and you’re at 455hp/473tq....... keeping the hp/tq per ci the same.

Plus, if using those big SM heads, the 400 will be less forgiving to having the combo be “off”.