Most guides are knocked out rather than pressed out, you need a guide drift for this, Goodson tools sells them in different sizes, I always replace with bronze and they are installed with guide drift and tapping them vai a hammer. On some egnein i find it necessary to press guises out, a MGB, but not a 1500 or A series engine, some have guide drift that work with air hammers to do this. Here's the deal though after the new guides are installed they have to sized for the valve, which means you need reamers and flex hones to do that job properly.
I think people who have never used a press look at it as do-it-all. Pressing guides out can actually be very scary/risky, and even with some heads cause them to crack, this is very true with MGB heads with stock cast iron guides, I do press them out, but only after they are initially moved a bit with guide drift by the hammer first, it's that intial pop that breaks the guide loose that can be the head cracker. That why you won't see most machine shop use a press for this job, most shops opt for the air hammer method for guides.