It is nice to be the bearer of good news.
I have just checked the bits of the Durant Bypass which have been advertised so far--job piece numbers 18847(04), 18847(05), 18847(06)--and it appears the bypass is to have full control of access with comprehensive grade separation of all intersecting roads. It will, however, intersect with existing US 70 (in the west) at a flat intersection.
However, US 70 is not being bypassed all the way around Durant in the current round of construction. The bypass will have a temporary terminus at a flat intersection with a shoo-fly detour of SH 78, just past the location of a future bridge which will carry SH 78 traffic over US 70. Just two intermediate interchanges are being built--US 69-75 and US 69-75 Business.
I don't know what the speed limit will be because so far the only plans available are all for grading and bridges. Signing on the US 70 bypass mainline will probably be part of future paving contracts.