Seat question?

We have some free bucket seats. 1978? Ram charger style. They are low back. Bottom of shoulder blades for me. Pretty much the same height as a 1970s bench seat. 
now, since we can't use the factory 3 point belts due to seating position moving and roof chop/slide, we have to use 5 point harnesses. Obviously the seats have no provision for the anti-sub strap. Any reason we can't cut a hole for the strap? Are low back seats a terrible idea with harnesses? Thanks!

General rule about safety is if you question if it's safe then it probably isn't. 

A 5-point harness with no head restraint?  Am I missing something here?

In reply to trucke :

Per the rules: a car may use factory 3-point seat belts. If they are not present or cannot be used because of seating position change or if the car was not equipped with them then a 5 point harness is mandatory. Or something like that. 

I... would put my personal safety above the way the rules are written in this particular scenario.

Matt B said:

I... would put my personal safety above the way the rules are written in this particular scenario.

Yeah my 2020 car has a factory seat with the headrest removed and a 5 point.  That's going away

So it's a 79 thunderbird so the factory safety feature was sheer distance from any possible impact. The roof has been chopped and the driving position moved about 6" so the original seatbelts won't work. 
Seeing as we plan to drive from UT to FL in October I'd really like to pass tech when we get there. The usual answer of having a local safety steward look it over isn't really an option since we live in a Motorsport wasteland and the closest club is several hours away. I'll buy high back seats if I have to. Just trying to be compliant. 

I... Get the high backs.

EDIT: I hate when someone tells you what to do and doesn't explain themselves... The way I see it is that the rules are intended to make this safe, and that would not be safe. It's the sort of partial coverage that reminds me of someone on a motorcycle in a helmet, shorts, and flip-flops. I just can't see the headrest thing being other than an omission which would be fixed for next year's rules once you show up.

That of course gets into competition, your budget, your decision about whether you're comfortable using that loophole while it exists. It sounds unsafe enough to me that I wouldn't use that seat anywhere I genuinely felt that safety gear was a good idea.

In reply to Ransom :

While I understand that some folks would be competitive enough to exploit a loophole like that, I just want to have fun. As far as the drive out there, I'm ok with a lap belt, same as a Jeep and better than a motorcycle. But there is a very real possibility that we're over the ton in a quarter mile and if I didn't think that 13.49 was in the cards I'd leave the top off the car. A cage isn't really in the cards though so I'm just trying to stay within the rules. And I really appreciate all the input. 

Trailering to Challenge, or driving? I would personally do a better seat, either way, but ... I have a lot of miles on two wheels and I learned in Los Angeles traffic. I have moved alongside a car to let the car behind me hit the car in front of me. I have been rear ended in a car. I would fear the drive more than the challenge.

What kind of seat should I keep an eye out for? I could likely drop something off during the summer.

Matthew

In reply to matthewmcl :

Driving. Slowly because big carb V8 and no overdrive. Anyway, I can find seats, just getting some hive weight on my free ones. Thanks though. 

Low back seats ruled out. Any problems with cheap catalog racing seats? 

Nothing against those, but be aware they are brutally uncomfortable.  If your making a long drive, think about padding at a minimum.   Even with pads expect a miserable ride.