The PPG 60080 crosses to Martin Senour (NAPA) 10091 in accordance with the MS on-line cross reference
. I have no idea how close it is. You can also look up Allis Chalmers in the fleet section at the same site and get several
formula numbers for AC persian orange. Again I have no idea which is which or if any is close to that early shade. There were too many possibilities for me to try test sprayouts. Interestingly, using the MS listing for Allis Chalmers, the 10091 does not show up at all, although a 10090 does. I gave up on MS when I was looking because of conflicting info and MS color chips for the several numbers they listed all looked similar - all were too red.
Unless you are searching outside the PPG brand or for a higher quality than OMNI, OMNI MAE 60080 is an excellent match to the MTK 60080. It is, after all, the same color number. It is an acrylic enamel that can be used as a non-iso paint. I think you are going to have some difficulty if you are looking for a high-end non-iso mix in any brand. PPG's Delstar (DAR) 60080 is a great AE, if you can find it in your area. It would be a prime consideration as it can be mixed non-iso. At least it used to years ago. I also thought that the Centari YS074 looked pretty close from one of your test sprayouts. That's a nice AE that is still mixable as a non-iso paint. Many would call me nuts to refer to Centari and Delstar as high-end since that would be considered an oxymoron nowadays. However, they are both excellent AEs IMO with the price to prove it. Anything of higher quality or performance is going to get you into the urethane area with isocyanates in just about everything. Unfortunately for me, Delstar is no longer marketed in my area. Centari may not be far behind. Neither can compete with the urethanes in performance or with the "economy" line AEs in cost.