The best thing to do is post pictures of what you have. If the radio equipment is FM band and has a gold AMA sticker on the back then it could be used. As Hydro pointed out you will need to replace batteries. For the transmitter it most likely used a 9.6V nicad pack. It may be a search to get the same nicad pack. Options could be a 11.1V Lipo or a 9.6 LiFe battery. I personally would go with the LiFe. Same would hold true for the receiver and servo battery, a Life 6.6 battery. 95% of the old servos can handle the 6.6V just fine but to be certain a google search of the brand and model number will confirm. If the specifications state 4.8 to 6V you will be fine. All battery chargers available these days will handle all battery chemistries. Servos, most are compatible. If you have Futaba which there were 2 connector styles made. Pre 1983 they had a G connector which has 2 visible pins. The J connector is a rectangular plastic connector with the pins internal. The wire color coding is the same, red positive, black negative and white signal. If you have JR radio then you have a J connector. Red positive, brown negative and orange signal. The JR and Futaba J connectors are compatible. If by chance it’s an Airtronics radio, I suggest a new radio. If by chance you decide on a new radio the JR and Futaba, as well as any servo with a J connector will be compatible with new equipment. Spektrum has the market share right now and is reliable and good customer support. Being a popular brand means help is as close as your local club.

Helicopters, again post pictures. I am familiar with everything made 1975-1995.