The way to add an AH is another point of doubt: I feel little inclined to invest solid money in outdated gyroscope technology. But the alternative would be a major panel redesign with some kind of EFIS - not a job for a lazy Sunday afternoon.
Perhaps another alternative, not EFIS, but I believe you can get electronic laser ring gyro based AH's - don't know about certification status, or whether you care, but they'd not be outdated, nor wear out quite like a conventional 'hard' gyro, nor presumably cost as much as EFIS.