It isn't often that we share specifics on things such as gaskets but I just had the joy of changing the
oil pump in my 289 while the engine was in the car. I have an Aviaid pan that is somewhat difficult to remove over the pickup and there isn't a lot of room between the pan rails and the chassis. I picked up a Victor Reinz 1 piece pan gasket #OS32491. This will fit 289/302 in most production varients. The quality is fantastic. It is made of a product they call " Victo Tech" which is a high grade moulded rubber and silicone. It has built in load limiters which are small metal washers moulded into each bolt or stud hole to retain constant loading of the fasteners. ( The gasket will not squeeze out) They also claim "excellent heat resistance". I like the idea of the end seals and the side rails being attached as it eliminates the potential areas of leakage where the endseals normally meet the pan rails.
I'm sure they make the same type for other applications but while laying on my back wrestling with the pan, I'm glad I didn't have to worry about fitting together all of the pieces of a conventional pan set. Give it a try.
Rick