Hi Randy-

To be specific… In 1957 Winchester catalogued three different competition M70 rifle styles.  All had the uncheckered marksman stock with beavertail fore end, checkered butt plate, and adjustable hand stop, and scope blocks on the barrel and receiver ring.  None came with metallic sights (Lyman 77R and 48WH) unless ordered that way.  All three had a clip slotted action when in 30-06 (by this time the only M70s that still had that feature).  The only difference between them was the barrel:

The “Standard Weight Target Rifle” (formerly National Match) had the same regular weight barrel as the standard rifle, except with a special lower profile front sight ramp. Available in 30-06 only. The clip slotted action and barrel ramp are the main features that define a “National Match” rifle of this era.

The “Heavy Weight Target Rifle” (formerly just Target Rifle) had the medium heavy straight taper barrel (this is what it sounds like you are buying).  These were catalogued only in 30-06 (24″ barrel) or 243 Win (26″ barrel), although some were made in 220 Swift (before the 220 Swift “Varmint Rifle” was catalogued).  The muzzle end of the barrel had two D&T holes for a Lyman “A” block (not dovetailed like pre-52 M70 target rifles).  Only the 30-06 was clip slotted.

The “Bull Gun” (always called “Bull Gun” as far as I can tell) had a 28″ extra heavy barrel and was chambered in either 30-06 (the rarer chambering) or 300 H&H Magnum.  As with the target rifle the muzzle end of the barrel had two D&T holes for a front sight mounting block.  The 30-06 was clip slotted and the H&H was not since the bridge had to be relieved for the longer cartridge (besides the fact that clip slots would have been superfluous). 

Hope this helps.  Please post some pics when available.

Best, Lou