I have a 402 bbc bored .040 over,in the last rebuild I put in trw forged pistons,427 steel truck crank with arp 2 bolt main studs,line honed,3/8truck rods that I polished beams,resized,best arp rod bolts,magged,shotpeened. heads are 781 2.19/1.88 valves,pocket ported by me,short turn work,polished exhaust ports,new arp head bolts,block and heads decked, I was running a B&M 174 blower on this motor for a season and half,i'm a regular weekly bracket racer,car is 1979 malibu 3450# glide,3.50 gear,ran high 11's with that setup,maxed that blower out at 8# boost,decided to step up,sold that blower for $1000,bought 8-71 for$2350 from dyers comeplete kit,my 60 foots went from 1.70 to 1.80's with 5# of boost(20 percent underdriven)average run is now11.0 123 mph,best time 10.68@127mph 1.58 60' on a real good air day,I now have 2 seasons on this big blower,I put 3.70 gear in,now 60' is 1.70 average,I think i'm makin 600 hp on good air days,i'm think carbs are rich,square 84 jets in pair of holly 750 dp's,NOW FOR THE QUESTIONS How much boost is safe to crank into this engine? I would like to run low 10's@130-135,I have the stock crank key with a very tight fitting fluidampr,I have pulleys for 6# boost or 8# boost,I also have a set of 3.89 gears I can try,I have 3 and 1/2 seasons on this motor now(about 300 1/4 mile passes)4800 stall convertor,transbrake,leave on 2-step at 4200rpm,no tire spin,shift at 6200 to preserve parts,but will pull to 7000,mild hydraulic flat tappet cam