Turn a small drill press into a Bore/ Hone. Bolt it to the top of your engine block & do your own machining .
Agreed on all of this. Maybe we should be thinking of a member who's normally a pot stirrer, but is being unusually quiet on this one...
that's the 'ah ha" of it.
Back to that hyd roller spring idea..
Personally, I would consider the 170lb seat pressure to be a bit more than a plunger wants to manage . I'd definitely use a light oil for as fast a refill as possible of the lifter when that much pressure fights pumping up at all.
Light on the preload too...you dont want to bottom out the plunger, itll run great.. but then kill the lifters and or cam. Shock loads rollers that aren't designed for that load. The travel has to be there for a fighting chance at A. Not bottoming out the plunger by pre loading bellow the range of recovery and B. Keeping it from pumping to point of float/hanging the valves open. The factory used a ton of preload because they wanted to use a spring light enough to keep the iron core roller cams from wearing out.. light a psi as they could get away with..for 200+k... and that massive preload .050-.090 would take up the slack in the upper range once the spring started giving up..which is right where the combo of parts as cast falls of, 4500rpm. Ask any cam grinder and theyll tell you a minimum 250/260lbs for any hyd roller turning 4500 rpm IS required...the factory said eh.. how about 200lbs and .060 worth of preload to chase the push rod..lol..but really they took and ground a larger nose flat tappet base 'larger probably' circle, it's just not steep..its soft.
For a small block...couple things... if the geometry has been corrected...I'm more a fan of 120-130lbs seat and at least 340lbs for a say.... .550 lift hyd roller turning 6000 rpm in a AT car ....360-380lbs for a dual purpose and or 4 spd motor. 170lbs seat is what you would typically use for a street solid roller chevy...where the bank is 48, geometry is set right and all the components are about 10-30 grams 'lighter' along with those softer ramps. You could play with that 170lbs if you're using it for drag racing. Mopar sb 58 banks and heavy everything need more pressure to control it.
Think lobe, rocker ratio, lifespan/usage , core type, geometry though when choosing springs is all I'm saying.