Firstly, sorry if this is a bit of a "newbie" question, I'm still quite inexperienced with large format, I'm more at home with 35mm/120 but I'm trying to learn

I have a Graflex Crown Graphic with a Schneider Krueznach Xenar 5.6/150 lens. The camera is in very nice condition and the rangefinder was calibrated before I bought the camera, and still appears to be accurate.

However, I'm finding that this lens isn't really ideal for portraiture. It's too wide angle, and I'd also like to have a closer minimum focus distance. But I have no idea in what's involved changing lenses on this kind of camera. Obviously it's not like a modern SLR!

I get the impression I'd need to change the lens and lensboard and recalibrate at least the RF. Is this right, and is it worthwhile? And is this easy for a LF newbie like me? Or should I be looking for a different camera for portraits in 4x5?

Thanks!