Thanks!
I didn't draw any template sprites for 64x64 tiles since most of the detail sprites are smaller than that. It would be like very large tiles with very small details, like how the 8x8 tiles now are very small tiles with very large details.
Most retro games tend to just upscale the entire game without any interpolation, such as x2 or x3 pixels per pixel. Additionally you can add an interlacing and blur effect on the screen to make it look smoother. I did it in Surgevania