The Win M70 featherweight came out in about 1953 in the short chamber calibers- .308 and .243Win (the .308 necked down) and the standard issue barrel for the featherweight was a 22"- without the "goose-egged" rear sight lump found on both the Std. wwt. and the Std. Wt SG series-- There is NO rear set screw in the FW stock, as on the Std. Wt. pre-1964 M70s--
In 1951 WRA changed from the single hook cut rifling, a process which took 11 minutes, and then the finished bores were lapped with lead compound- WRA went to the button broaching process and eliminated the lapping, except on the NM and SG M70's- The featherweight was an attempt by WRA management to lower mfg. costs- but using a anodized (ugh) aluminum magazine and floor plate.trigger guard assembly, also an alum. buttplate instead of steel- a shorter barrel w/o the taper you mentioned as found on the 24"-25" (.375 H&H mag. and some .300 H&H mag. M70's- and 26" as on the .220 Swift and the later .264Win. cals.
Tricky thing here is, up to about 1962, WRA still had the custom shop concept, so you could order a M70 FW in SG in 30-06 with a 24" barrel (a scarce variant today) And as this is a shotgunning forum mainly, greatly enhanced by both the German-Austrian sectors, as well as the fine rifles sector, and thanks to Dave Weber for that- you can also consider the WRA tried the same concept with the Model 12- in the same aprox. 1953 time frame-- the M12 featherweight-
My prejudices here I suppose, as I shoot better with a std. weight (albiet well balanced) weapon, but I'll always go for my pre-1964 M70's in std. grade, and my M12's also in std.- featherweights ain't for me- might be just right for you!!