Are those parts ACTUAL OEM components, or cheap-junk aftermarket replacements?
Knowing Holley, they're bottom-feeder aftermarket replacements for the OEM-quality parts--which might explain your failures.
Point being, it was wise of them to use OEM-compatible designs, but they should have used actual OEM parts. Replacements will be available for a long time...but you're likely to NEED replacement parts.
I was merely stating that contrary to the OP's comment there will be parts availability, and yes, I know they used bottom-feeder parts. "might explain your failures"? Bottom-feeder crap does explain my failures. I've stated both sides of Sniper ownership, and fairly often. It runs great once you get all the nickel and dime bits to get it to work, and then you end up replacing their cheapskate sensors.
Bought a complete sniper kit from summit. Holley complete kit.
My local engine guy has 3 cars in his shop broken down sniper and another brand with fuel issues and no parts here.
Even the holley unit is cheap junk and $1500 for the kit plus freight and import tax.
I sold it
There cheap junk and it no more than a tbi basicly
At the time I bought mine, Holley was selling refurbished basic Sniper kits for $800. Totally worth it - except that you need another couple hundred dollars of AN adapters, throttle adapters, etc. But as you said, the factory TBI can't handle 400 hp without serious mods. I'm not anti-carb, I wanted fuel injection reliability - and I've gone so far as drilling my own jets for carburetors in the past.
Not trying to dissuade you from going carb if you want to, I just wanted to clarify that Sniper parts are available. Then again, I'm in the US. Australia might be a different matter.