Suggest You review AD's and SB's for Your engine and narrow-down either the recommended borescopes... available or obsolete... and/or define the borescope functional requirements... and have conversations with borescope OEMs regarding your application/requirements.
IF your requirement and the old/obsolete borescope is a 'known issue', then reputable borescope OEMs should be able to assist... and if anything describe alternatives to the 'obsolete borescopes called-out in old tech. OR, recommend contacting 'Brand X' who made the original equipment... for their 'equivalents'.
Then, when the requirements are validated and available equipment is proposed... ask for an on-engine inspection/demonstration for validation... preferably with Your designated engine OEM tech-representative 'leaning-in over everyone's shoulder'... during the demonstration.