If you are new to Toyotas and the 22RE, I would highly suspect that your timing chain guides are FUBAR if they are original. If so, your oil pan is full of plastic timing chain guide pieces and will have to be removed as well to be cleaned out.

The good news is that you really should remove at least one or the other - oil pan or head - to properly install the timing chain cover w/o screwing up your head gasket. Both is best, but not necessary.

When you remove the timing chain cover, keep meticulous track of which bolts go where. Seriously, label them or do something to be sure that they go back in the right holes. Another PITA I learned when two of them got mixed up without me noticing.