OK, a couple of things.

First of all, I'm not familiar with those flashes, but if they're Vivitar 283-class output flashes they should work. Or iow, about the same or more power as the old Nikon SB-24. You can of course use less-powerful flashes for bounce flash but you must take care; more about that later.

The flash-to-subject distance using bounce is of course from flash to the ceiling and from the ceiling to the subject, but bear in mind that there's _lots_ of light loss, I think generally two+ stops with an ordinary white ceiling, so it takes much more flash output to do ceiling bounce than direct flash or even if you use one of those relatively useless bounce gizmos.

If you're letting the camera fend for itself, most likely it's selecting an aperture that would demand far more flash power than is available, so take it off auto and manually set an aperture of f4 or so, assuming you're using EI 400 film. If your flash is one of the less-powerful models you may need to set the aperture to f2.8 or even f2 to assure sufficient exposure.

Another thing you can do when using ceiling bounce is use a kicker card; this is a small piece of white card (a business card is fine) attached to the back of the flash head, when the head's aimed upwards, that kicks just a little light straight ahead. This can prevent dark eye shadows when working close with bounce flash plus of course puts a little more light forward rather than behind you.

Also be sure you're not aiming the flash behind the subject; it should be aimed at the ceiling roughly 1/3 to half the distance from you to the subject.