If RTX 2070 and RTX 2060 Super are the same price go for RTX 2070 as the RTX 2060 Super is a cut down RTX 2070 (TU106 GPU die). Normally those are $400 though.
The lowest I'd go is with RTX 2060 non-Super which is $330-350ish these days , that has 192-bit memory bus and 6GB GDDR6 VRAM. I don't think you're going to find anything worthwhile in the long run at $300 , because on the gaming GPU side that's GTX 1660 Ti and on the professional side it's Quadro P1000 which is below GTX 1050 level (it's a GP107 with 640 CUDA). There might be lower Turing parts in the pipeline since on notebook/mobile there are RTX 3000 (TU106 die with 2304 CUDA similar to RTX 2070, 6GB GDDR6 on 192-bit memory bus), T2000 (TU117 die , 4GB GDDR5 VRAM so not worth it) and T1000 parts. Normally all Quadros are around 2x the gaming counterparts due to binning for significantly lower power.
If it's Autodesk with Revit architecture and rendering is involved the Ray tracing cores are going to accelerate the workflow so much that GTX 1660 Ti is pointless.