if your cam has enough lift, the Windsor bottom end will cause you to need to change the pistons for the Cleveland valve relief
to live at 8k the Cleveland block should have lifter bore bushings installed to control oil pressure & volume loss especially on the side that the main bearings are fed from, the other side can use a restrictor in the passage under the rear main to the lifter galley
WydendorfMachine.com - Wydendorf Machine
there is also an external oil line mod that helps, it feeds the rear of the engine the same as the front, connecting from the oil port near the fuel pump to the oil sender port
also think about internal balancing. stock external balance is fine for low rpm stock duty but internal is better for 8k. if you stay with external balance, the balancer on the front needs to fit on the crank TIGHT or the block WILL fail at the 2nd main web
and fill the jackets with grout as high as you dare, word is that any closer than 1-1.5" from the deck will cause cooling problems. Embeco 885 is the same stuff they sell but before the $ mark-up, i paid like $40 for a 50# bag. i've seen blocks filled all the way and water re-routed out the front of the heads to a Tstat adapter like they use on race Clevors, or you can use a greased rubber hose to hold the passages from the water pump into the block open and fill it close to the top, then pull the hose out after it sets
FWIW i think the Windsor may be slightly stronger on the bottom? but not much if any, certainly much more plentiful to replace a block or stock crank though.
for Clevor pistons and intakes look at TMeyer, Inc. Precision Automotive Machining
or look up Icon pistons available through Summit, they use a chevy pin so you'll probably end up with an aftermarket crank & rods that route
going 8k plan on a light or ultralight crank, and titanium intake valves & retainers forget about the stock(junk) or even stainless(too heavy) valves right now!
BTW there's a Crane F-276 on ebay