GM has always had problems with technology. GM has been toying around with AFM/DOD since 1981 (6.0 Cadillac Big Block), and still cant get it right. OHC would solve a lot of the AFM/DOD problems. But GM cant even get that right.
Ford has been running OHC on every single mass produced engine since what, 1997?
Dodge has been running OHC on every single V6, and I think I4, motor since 2012, only not doing it in the Hemi, which is no longer being made. And Fiat/Dodge/Jeep/Chrysler is rated the worst auto manufacture in the WORLD!
Toyota/Lexus since the 80's
Nissan/Infinity since the 70's
Benz since the 60's.
Kia/Hyundai since the 00's (If not earlier, like the 80's)
Im not putting Audi/VW or BMW on this list. Any vehicle you have to replace rod and main bearings as part of routine maintenance doesn't deserve anyone's time or money.
Chevy... Nope, lets continue using the same technology that we have been using since the 60's on our V8's.
In all reality, I cant blame them. There is a reason that the early (1999-2006) LS engine are rated one of the most reliable engines ever mass produced (with a few exceptions like the LH6).
I cant think of a single good GM OHC engine... EVER. The Z06 Vette engine from 92 wasnt even a GM (Lotus). The GM 2.0 and 2.0 Turbo from the 80/90's had head gasket issues.... Now that I think about it, every single 4cyl engine that was OHC from GM had head gasket issues (except the Atlas 2.7, and the 2.7 TurboMax), or turbo issues. The 3.6 is rated one of the worst engines ever mass produced. The last good GM V6 was the 60* 3.5 engine that was built for 3 years (2005-2007), and the 3800 although it had its own share of issues.
I mean come on GM...
My boss just bought a Silvy with the L87 that is affected by the recall. They currently dont have a solution, and GM is only replacing engines that have already failed, with a backlog of 3-20 months! (depending on region). Its to the point in some areas that GM is just buying the truck back for sticker.
Edit: Just adding another opinion here, the 2.7 Turbomax looks strangely like a 2.7 Atlas with a Turbo.