250-500cc Side Exhaust Valve Removal?

I'm finally getting around to stripping down my 300 cylinder to get it sent off and plated.

I've run into an issue though, how do you remove the side exhaust valves from the cylinder? They've got a bearing pressed in on top, with nothing to pull on. So, I figure you've got to press them out from the inside somehow, but how would you go about this without damaging the cylinder or bearings? My other thought was maybe with plenty of heat they would more or less fall out, beings when there are retainers that hold these in place when the engine is all together (I cropped them from the parts image below).

There is a 6x1mm threaded hole that you can screw a slide hammer adapter into.

I took another look, and yep, you're right...well mostly. It looks to be 5x1mm rather than 6mm.

Not sure why I didn't think about that, but makes perfect sense. Thanks.

ohh i used a blow lamp and my largest flat head.. now i shall have to buy a slide hammer

And another update...that'd be a 4mm bolt...picked up a nice shiny stainless steel 5mm bolt and washers to fashion a puller with (combined with a flat block of aluminum with a hole drilled through it), and get home and the dang thing is still too big.

Oh well, the 360 is back to running pretty good again, so maybe the 300 will sit in it's box a little longer.