I want to save by using cressida wheels of a 78Datson hatc..

Is safety grossly affected?
Changing factory rim and tire size my be a big deal. I have a 78
datsun . Tires from the 79 cressida bolt on to the Datsun fine. The
datsun has factory 13 inch rims with tires width of 155 and 75 and/or
80 for the outer rubber to rim distance. The Toyota has 14 inch rims
with 185 or195 and 70 for the rim to outer rubber, slightly shorter so
the rim is closer to the road. It has a five speed trany that should
be enough gears to deal with it. I have to see if the front tires
would snag on a bump or turn for the final step.

One of us doesn't understand how to calculate tire sizing and I think it's you.
That smaller number is a fraction, not an absolute number.
.75 X 155 = 116.25
while .70 X 195= 136.5
So the 14" tire has a BIGGER absolute height.

You are making a large difference. If it fits and drives OK, I'd be all for using my available tires and saving money. Test out the braking and handling and adjust to the differences. And don't go over the speed limit be mistake. Your gauge will read way low.
You can calculate the circumference difference.
You can go to a tire site and read the difference.
Or you can go to a measured mile on the highway and time or compare odometer readings.