If you can lock them up, at all, you are normal. Since the rear shoes are new, I wonder if they were arced before installation. If not, they will stop better as they wear in, and that will help somewhat.

I have two drivers that have Huck brakes, 1/2 ton and 2 ton COE, the latter has a booster. Both can lock up the brakes but you still have to drive defensively.

Keep them adjusted, so the pedal doesn't have to travel too far when you brake hard.
Good luck,
Kent

1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix