Journals should run in the 1 to 1.5 clearance. Up to 3 is allowed. Well, keep that center main tighter if you can.
You can still find "plastigauge" at various auto supply houses, but I find I can do it by "feel" just as accurately when the engine is upside down in a stand. Keep removing shims (or God forbid shave the caps) until it gets "tight" and then put a thin shim (or paper) to first one side or the other (or both)
This really the sort of job best done with the engine out of the car. It's not that hard to remove.
As to valve guides, they're available and not too expensive. But if you're doing the guides maybe do the valves as well? (They're worn after all) And if doing the valves then why not the...well, you see the problem here. This a sort of thing that "snowballs."
Keep your valves numbered so they can be returned to the same holes. Remove the springs/keepers with a spring compressor. Using the open valve stem as a guide, apply the valve guide removal tool and give it a sharp rap with the hammer. You can use a screwdriver for this but you run the risk of chipping the tops of the guides or marking/galling/breaking the valve stem.
With everything apart you'll want to carbon clean things up and maybe grind in the valves a touch? At least to establish "seal" if at all suspect? Oh yeah, any cylinder carbon. (head off)
With the guides out, you can put in new guides from the valve chamber without disrupting the lifters if they're adjustable. I.e. this a warning not to mess with these unless your feeler gauge shows the clearance to be incorrect. Solid lifters you're pretty much stuck unless you dare touch up the ends of the valves CAREFULLY to restore the normal clearance. (Don't overshoot in grinding or you'll be back at grinding that valve seat to try to decrease clearance.)
Assembly is basically the reverse of dis-assembly from here on.
Wot compression ratio is that Simmons?
Joe K