New oil pan / gasket help

[Hi-Fi]

I lifted the engine to replace the oil pan gasket and once the pan was pulled I found that the issue may be due to the pan itself. So I want to replace the pan and gasket.

From research I found that I want to use the blue Felpro 1 piece and the pan is the only thing determining if I need the thick or thin gasket. I can't seem to find out what pan I need though. Any help appreciated

Engine is a 350/383 in a swapped 87 LS, not sure what year or what it's out of. Dipstick is on the drivers side.

Thanks for any help....I WILL GET IT ON THE ROAD THIS YEAR! ( I hope)

 

[MrSony]

https://www.speedwaymotors.com/the-toolbox/small-block-chevy-oil-pan-gaskets/28651

 

[bracketchev1221]

Best thing I can suggest is to lay a straight edge across the pan rails and measure down to the bottom of the recess and see what pan is in there now. Then you'll know what they used. Otherwise, block year means nothing. The pans were interchangeable.