autoinstr1

hello all I have a few questions about this 72 year old truck ( owned by me , a 72 year old man). Yes we were born on the same day. It is a 1949 dodge b1d, long bed one ton. 1) the rear brake cylinders have 2 different size bores, one larger and one smaller. Does the large bore face the front shoe or the rear shoe? My theory is small to the front ( less pressure on the self actuating shoe ) and large to the back (more pressure on the rear shoe) 2) Can the rear shoes be adjusted by measuring with a feeler gauge thru the drum slot ( first the major adjust on the lower anchor and then the minor adjustment by the cam bolt? 3) Is there any radial tire that can be used to replace the 750X16 tube tire on these slit rims? Thanx for advice, Thom S.