I absolutely guarantee you can get chrome lined bores reamed to whatever diameter you need that is safe. Although retired, I am an English trained shotgun-maker. I had a specific set of reamers for use on chrome. Just find the right shop that has the ability. Turnbull Restorations is another one that comes to mind. Kirk Merrington in Kerrville, Texas and Stephen Hutton at Brittania Sporting Arms in Portsmouth, New Hampshire, maybe Charles Schneible at British Sporting Arms in Millbrook, NY. In California I'd ask Dale Tate at Camanche Hills Hunting Resort. He might not have a reamer for chrome but he can certainly refer you.
Back more than 6 years ago we charged $60 per barrel for steel and $95 for chrome lined. Of course, that has likely increased since then but it's not going to break the bank.