225 slant rebuild for more power

A ‘64 Valiant wagon is a very cool car.
While the engine is out for improvements, invest some effort in proving the brakes. Those old school drum brakes are no match for the stopping power of the modern cars that will be on the road with you.
Inspect the brake lines, replace the steel and rubber hoses as necessary. I have had good results with the steel lines from Inline Tube. Up grade the master cylinder to a modern 2 chamber unit and look into disks for the front. Good luck with the car and make it your own.