Do you feel the use of cheap parts has contributed in any way?
not in the slightest
not unless you count using ARP2000 bolts vs the ARPL19 bolts as being 'cheap'
indeed i used one of those ebay gasket kits, and used camshaft seals, cop seals, water bridge seals, waterpump seal, head gaskets (which looked entirely comparable to the HKS mls units i used on my last engine) timing cover and vvti seals, intake manifold gaskets, exhaust gaskets.
absolutely zero issues with any of those parts following around 20hrs dyno time and around 60 or 70 full noise dyno runs up to 10k rpm, and 1 test and tune at OP running around 70 odd laps.
on disassembly there was no indication of gasket fragility or prone failure. zero issues right there.
of course you make budget related decisions when building things, noone has bottemless pockets, but i hardly think this is an area where youre talking about the risk of a catastrophic failure. theyre just gaskets!
i use genuine timing belts, timing tensioners etc, genuine valve stem seals, and run custom rings etc. bottom end was all ACL race series
new engine will again use an egay top end kit mainly for the water bridge/ head gaskets and intake/exhaust gaskets
bottom end is getting special treatment indeed!