I've got a couple questions on doing a tall fill on a low deck stroker project. Do you typically fill to the bottom of the water pump hole, and is 1 pail of hardblok for a tall fill enough for a big block engine? Thanks!

One thing to look for when filling to the bottom water pump hole., is leave it 1/2" shy of the bottom, the head bolt castings hang down from the deck in side the water jackets, and sometimes when you go even with the bottom of the hole it will touch some of them creating pockets or flow issues with your coolant. I always used the moroso filler, one jug per side.

Why do you want to use fill in your block?
Have you had it sonic tested? If not I would
If it has at least .160 cylinder wall thickness after boring on the major and minor thrust sides of the cylinders DON'T use hard block or any other filler
All fillers end up creating two different heat zones in the cylinders, NOT good
I've made over 800 HP on a stock 440 block and a little more on a 400 blocks with no filler with no problems sealing or living at the track and on the street

Cab, my block from my little 451 was not filled and finally cracked, so I am going to fill the next one. This engine only made a little over 700hp but I bracket race most weekends from May thru September so it gets the snot run out of it year after year. The block was sonic tested but don't recall the numbers off hand.

My engine was hardblocked, and still cracked the cylinder wall...

if you want your rings to last like your old motor did do NOT fill it
The last motor I redid for a NHRA stock class racer( 3/4 filled1971 340 motor built by Greg Luneack(SP?) originally) wore a set of rings out on the dyno while testing cams and heads, less than 70 pulls Those rings were back cut 5/64,5/64 and 3/16 oil rings
The dyno owner used his hand held infared thermometer to read the outside block temps on the dyno while running and after cooling it down for the next pull. The owners like to pull the car out of the staging lanes with less than 100 F coolant temps and have 110 to 120 F leaving the line so we where using 120 F as the starting point on all the pulls.
We found that with the head temps and upper block (above the fill) at 120 F while the lower block would be around 180 to 200 degrees depending on how long we let the dyno water pump circulate water through the motor :shock
It would take over one hour to get the lower blocks temps down to 120 F with 60F dyno water temps going in the motor That was testing in the spring at night in the high desert part of the Mojave desert in Hesperia, CA with 60 F outside air temps or lower
I've seen a lot of RB blocks,413, 426 W and 440 blocks with crack main webbing, filled and not filled
No 400 blocks yet with crack main webbings regardless of the HP made with no fill, broken main caps yes Cracked cylinder walls also
Your best bet is new race block to start with