Plug and Play HDMI low lag 720p Adapter
 
This is a plug and play HDMI solution. No modification to console necessary to connect to a modern display.
 
I've tested this and it will give you a decent picture with almost zero lag, if possible this will use s-video as a base signal to process into HD for modern displays and if s-video isn't available it will use composite. S-Video will give you a better image.
 
Tested with PAL N64, uses S-Video
Tested with PAL SNES, uses S-Video
Tested with Super Famicom uses S-Video
Tested with Super Famicom JR uses Composite, requires a small modification for S-Video
Tested with PAL gamecube uses Composite 
 
I've attached some digital photos of the HDMI adapter output from s-video modified super famicom junior.
 
This is an official bitfunx upscaler in aluminium case. Compatible with most modern displays with hdmi input. This is good quality hardware designed to process the analogue image into a digital HDMI signal with zero transmission loss and miminal lag.
 
Don't settle for the cheap converters these are junk and won't scale the image without signficant lag!
 
4:3, 16:9 aspect ratio switch.
 
Includes HDMI cable and instructions
 
No external power supply required.
 
For use with:
 
PAL and NTSC SNES/ Super Famicom
PAL and NTSC N64
PAL and NTSC GameCube