Just my two cents.
I haven't used a Fluidampner, but have heard a lot of people say they wouldn" use one if it was given to them. Doesn't get the job done.
I had a set of the Edelbrock valve covers, and the oil baffle for the pvc valve/breather is a joke. Gave them away along with the plastic socket head capscrew plugs they came with to make them look like a two piece cover.
I can say from experience that I wouldn't waste the energy to throw the ACCEL distributor in the dumpster. Google it.
You can use a roller cam if you buy "retrofit" roller lifters, but they're not cheap, but may be less than a ruined engine from a wiped-out lobe on a flat tappet cam which is happening all the time now. Google it.
400 HP from a 350 on 87 octane? Aint saying it can't be done. Good luck.
To make higher horse power usually means raising the rmp where the torque is made. Raising the rpm usually means a cam with long duration. That usually means raising the compression to make it run efficiently, which usually means higher octane to keep it from self destructing from detonation.
Easier to make more torque with more cubes. If you are going to buy a new crank, might as well make it a stroker for a bit more money. Check out the cost of a 350 Scat crank(3.48" stroke) vrs. a 383 Scat crank(3.75" stroke) at Summit. With a 12cc dish piston, 5.7 rods, 4.166 bore gasket .039" thick, and a zero deck, the 70cc heads would make for about 9.6:1 static comp. ratio. and a DCR of 8.0:1 with the XE268 cam. 412HP using Cam Quest software.