PRW Roller Rocker Issue

Looking for some feedback from experienced engine builders

A guy has a 360 built by a well known builder, for big bucks..........
The engine is broken in and dyno tuned before pick-up.........
Buyer puts it in his car and runs it for about 20 min when it begins to run ruff, fouls a plug, then stalls.
When trying to restar it backfires
Replaced the plugs, start it up and its ticking on #6
Pull the valve cover to find amongst all the 1.6 roller rockers there is 1 odd 1.5 rocker, guess where, #6 Intake
After closer look it turns out the lifter seat is jammed down or stuck. Is it just coincidence that its the one with the 1.5 rocker ?

Builder offers to supply new lifters and gaskets for the repair, but say the 1.5 rocker will not cause any issues, still use it when reassembling the engine.

Knowing that a 1.6 to a 1.5 rocker can change the cam lift by about 30%, I'm not comfortable with leaving that 1.5 in there. I'm told that cylinder will not make the same power as the rest ?

If you have the knowledge that I need, please voice your opinion on using the 1.5 rocker or replacing it with a 1.6

THANKS !