...... Does anyone have experience with the 35-70 and what would be a good adaptall2nikon adapter?
I have Tamron's 300/2.8 and have used(briefly) their 180/2.5 lens.
The 300/2.8 is difficult to focus on the D70s(focus screen is crap), but easy on the D300 and D800.
I only tried the 180/2.5 on the D70s and decided against getting it(stupid me .. didn't think I'd update camera to a better one at any point tho! .. major regret)
.. anyhow, you should be able to find a genuine Tamron Adaptall2 to Nikon adapter somewhere on ebay. They're fairly common.
I can't give any info on how other brands will operate tho. I don't have a spare(any longer) but can assure you that full aperture control will be available with your Adaptall lens(es).
I have no (obvious)issue with metering, and the aperture control is auto with the 300/2.8. I also have two of Tamron's T/C's, the higher quality 1.4x and the lower quality 2x from long ago.
Again, no issues with aperture, nor metering on the cameras that can be programmed with lens info.
(the D70s can't, so Manual mode must be used for the camera to operate .. but aperture is automatically controlled).
I have no experience with a Df, other than a brief test drive in a store(didn't like the grip) so can't offer any insight as to how well your combo would feel.
As for chipping any adaptall lens .. the issue is the intermediate nature of the adapter. You can't simply chip the lens as it won't physically connect to the camera(the adapter does this), and the adapter dimensions appear a bit marginal to take a chip itself(especially if you want a relay system of connections to the lens itself).
If you're looking for a genuine Tamron Adaptall2 mount, it should be called a N/Ai adapter(so you'd be searching for the term 'Tamron adaptall2 N/Ai')
The N/Ai doesn't describe non Ai as it does in some instances of Nikon lenses .. I think it simply means Nikon/Ai.
I've never seen an Ais version of the adapter tho .. may try a search to see if one exists.
hope that helps.