According to the Encyclopedia Astronautica website, an Apollo Command Module was 3.9 meters in diameter and 3.5 meters tall. That doesn't include the Service Module. Since the CM didn't have deorbit engines, you'd need some form of SM to perform the burn. It could probably be something similar to what was used in the Gemini program. That would probably add a meter or two to the overall length. Would that fit in a Shuttle payload bay? It might, or you might have to change the dimensions to make it fit.

So, we've started with a deviation from the Apollo baseline by creating a new type of deorbit engine. We may well have to modify the dimensions so it can fit in the payload bay or to optimize it for the additional crew seats. We're talking about a different internal arrangement to seat more people, different avionics to replace the obsolete stuff, new heat shields, etc. Just what are we reusing from Apollo? It sounds like we're quickly developing a new spacecraft here as the ripple effects from changes start multiplying.

One of the advantages of a lifting body design is greater crossrange capability during reentry. This could make the difference when it comes to being able to deorbit quickly or having to wait an extra rev or two to get within range of land. Trauma doctors talk about the "golden hour" where an injured person's chances are greatest for survival. The longer you have to wait to get people to a doctor's care, the lower their chances of survival.

Parafoils aren't perfect but they offer much more control than conventional parachutes. You can't control drift with multiple parachutes so you're going to hit with a horizontal velocity equal to the wind speed. Parafoils are landed into the wind like an aircraft and flare as they touch down. Properly done, a parafoil can touch down with little or no forward velocity. Combine that with a shock absorbing airbag or deployable skids and you can have a more gentle landing than by parachutes. It's possible you could give the crew some rudimentary guidance capability for the parafoil to allow them to avoid ground obstancles like power lines, too.

Your "two is better than one" argument falls short in one respect. If one of the modified Apollo capsules is damaged, the other wouldn't be big enough to hold everyone. Who gets left behind?