I’m not really sure how well I can help you with that as I’m not super knowledgeable as to how these things work. I tried plugging in an S-Video Snes connection to my Elgato. It registers it as either 480i or you can use a setting to convert it to 480p (Which when capturing looks much nicer). Same with Composite although it looks rubbish either way with Composite. I cannot capture true 240p with the Elgato HD. Although, I don’t capture much for 240p sources anyway. The extent of what I intend to upscale with the OSSC are Snes, N64 (Both RGB modded), PS2 (For PS2 and PS1 games), and Wii (For Wii and Gamecube games). This will only be using either Scart input or Component input. While, I’m not very knowledgeable on this subject I’m pretty sure everything I intend to use it for is already 480i or higher?
When dealing with 240p source material with the Elgato, I used the 480p option, sent it to my Avermedia, and then captured it just how it came out from that.
Sorry if I am unable to answer that question.
Also, if I was wrong about something (Which I probably was), please correct me as I hardly know what I’m talking about.