170 /6, Whats it worth? And where can I get one?

Since my Dart has hit the back burner sadly due to further and further issues arising, not with the Dart, just life in general, I am thinking of finding a 170 slant when I can afford one or trade a 318 for one and building a high revving twin turbo EFI 170 with an OD 4 speed and sticking it in my Dart so I can drive her around almost everyday without hurting my wallet too bad. So, what would a 170 slant and OD 4 speed setup for it probably run me realistically?