Roy,
As you can see, the lifters are the same for the GX270 and the GX390. Was that long pair of yours OEM? These parts are manufactured in several different places and I'm sure the tolerances are pretty loose (since they weren't designed for a high-lift cam). Anyways, thought you'd want to know.
GX270UT_Full_Parts_Manual.pdf
GX390T1_Full_Parts_Manual.pdf
Transmission.pdf
Transmission_Part_Numbers.pdf