exactly, t/cover first. in one of my previous posts here I mentioned removing the line up/placement dowels in the timing cover area in order to get the t/vover off. they are bit of a bugger to remove but it makes it easier to get the cover off without first dropping the pan. now that you have the cover off, with the gasket retaining lip broken, you can see why there is a problem getting the cover off without removing the dowels. anyway, lesson learned and you needed a new cover anyway. for install the cover goes on, then the pan as indicated. there is, however, a one piece oil pan gasket available that solves a few problems with the old 4 piece cork and rubber sets. all you would need is some clean surfaces and a drop or 2 of "the right stuff" or some good quality RTV silicone placed in the corners where they usually leak.
while the pan is off you may also wanna check the condition of the oil pan plug and the nut spot welded on the inside. if the threads are sorta not awesome now is the time to fix that issue as well. sometimes the nut can also split or crack because the piece of steel they use in there for the nut is not really much bigger than the hole for the threads. anyway, maybe worth a look see.if the plug has been replaced with one of those self threading over sized ones then you wanna check the condition of the nut as well for sure. the oil pan gaskets will require you to know if the dipstick is on the left or right, as seen from the driver's seat. see below for part numbers and description. there are also dual use ones, like the moroso one. when using an aftermarket t/cover there is also the issue with the depth of the groove for the front oil pan seal. some are deeper than others. ensure you get the right gasket.
https://www.speedwaymotors.com/the-t...-gaskets/28651
https://www.summitracing.com/int/par...et?prefilter=1
https://www.jegs.com/i/Fel-Pro/375/1880/10002/-1
https://www.jegs.com/i/Fel-Pro/375/1881/10002/-1
https://www.amazon.ca/Moroso-93150-G.../dp/B00CIJY5L6