If your TV is LCD, old LCD, then you need to use the best inputs the LCD has. Since it does not have HDMI, then what is the next best input ? VGA ? Component ? Scart will not look very good on a LCD, old or new, since the TV will likely be handling the scaling.
I wouldn't go for the rgbpi, the website isn't secure, they do not have any prices online - instead you have to send them your personal details just to get a price, and even then there is nothing stopping them from pricing you by region, not by the product itself - everyone gets a different price based on where they live. And, looking at many forums (I have researched this due to wanting a SCART output) they have many bugs in their software they link to.
I would get a PiScart, if it's scart you want. Or, get a HAT with VGA - if your TV has VGA.
