Radiator flow test
Plug lower hose with a tennis ball,something you can hold in place
plug upper hose outlet (Or just tip it back)
Fill radiator till top tank is full, stand radiator back up then release the tennis ball
should drain in 4 seconds (or "mississppis")
Im dealing with a barn stored car,though its in better condition than that one,I can sympathize with your pain.I take the small victories and make a day out of it,not looking at the end of the project,just the satisfaction of a days improvement..Id take my Dads late '31 coupe in that condition in a second (it survived the 'holocaust.' last seen in 1969) to drive your grampa's car,to breathe life back into it knowing he and your grandma drove in it to me would be very special.