The block you have is an early one - I believe it is VT149. VT328 is a later one. There are some differences but whole motors can be swapped. The early motors have the oil pump built into the main cap while VT328 has the pump bolted to the main cap. Crank shafts are also different and I do not know if they swap.
Some people claim that the VT149 engines were made for Case by Continental or one of the other engine companies.