Hi John I would doubt that, It must have been some other reason, like machining the head out to lower Compression, The OPS came stock with a hard chrome liner, so honing the new hardchromed liner out to strip the chrome, then re-chroming the liner, really would make no sense at all. I have seen a few of George's OPS engines, and they had machined out head chambers
I don't know about the OPS specifically, but pretty much every GMA engine I saw had the chrome stripped, great amounts of taper added, and then rechromed (because he had the means). Also in all cases, he lowered the compression *dramatically*, like, .060-.070 or more (with machined-out combustion chamber). To make up the power, he put in an enormous venturi. The GMA-Jett 50, as I recall, was .250 with a flush inlet. In some cases, with low-pitch props, the engines would quit right after release from fuel starvation from the acceleration. They all ran *extremely hot* by stunt standards, switched from 4 to 2 and back at the slightest movement, and had nearly no or "reverse" break, where the power actually seemed to go down when it broke.
For an example, original GMA-Jett 50 VS PA61 compression. We were checking with the pressure gauge (not the best way, but representative), spin over the PA, 125-130 psi. Same speed, same everything, GMA-Jett 50 - 35 psi. It also had a tendency to squeak audibly when running rich, and was extremely prone to sticking at TDC, even with the plug in. In that case, while I wouldn't call it "overcooling", it was clearly set up to work with the head/liner at much, much higher temps to try to take out some of the taper. Unfortunately, it had to run the same 1/2 horse everyone else's engine.
He told me he did that on purpose, because the first ABC engine he ever got, he ruined. ST X29 or some equivalent, the first ABC engine in major production, for rat. He turned it over, it squeaked and was tight over TDC, "obviously" too tight, so he stuck it in the Sunnen and "fixed" it. And of course ruined it. Since, he said that he was making darn sure any ABC engine had lots of taper and was really tight over TDC, like the X29, to avoid a repeat. Note that this was all over on the old RCO forum, anyone who was around can confirm.
Of course, the X29 at full song ran with the head glowing dull red, and a GMA-Jett 50 in stunt trim runs much, much cooler. The Commissioner and a few others had all sorts of issues with them (like breaking cranks), later got Dub Jett to make new liners with conventional taper, and then they ran well.
Brett