The sandrockets are cool. I have seen many in person at Glamis but never got a ride in one.
I have seen them with small block chevys and big blocks. I have seen one with that old aluminum V-8 I think Buick made? I have also seen one with a turbo v-6 out of a Grand national Buick and that thing rocked. The weight savings seemed VERY apparent.
They make (or at least made) them in two and four seaters.
I see no reason that a person could not make one out of ANY powerful motor (i.e. four banger turbo, Honda T-tech) etc. For an reliable machine that won't break the bank to build.
The only thing I did not like about the Sand Rockets is they have the motor front and radiator rear (That parts OK.) But they actually flowed the coolant THRU the frame tubes to get it back and forth. I prefer NOT to run something through stressed members of frame that WILL corrode the tubes to some degree and eventually badley. Just me maybe but I would make separate tubes for this purpose.