yes, the 700R4 transmission is the standard trans for the K1500 with a 5.7 350 engine. 305 is also with the 700R4 transmision.
Yes
yes
Yes it will fit right on the back of any SMALL BLOCK CHEVY ENGINE from late 1999 down to 1955.
no
Yes...they are the same bolt pattern.
1.5:1
Yes, a 283, 305, 307, 327 etc will fit. You should be able to use small block motor mounts from 1966
Yes you sure can. There the same.
yes a350 trans and 400 use the same bellhousing
Jack up the motor and replace them. Center of the motor on the sides. Use a block of wood on a floor jack and lift on the oil pan,
a very easy swap...use the original trans