Mid to late 70's, that is over 30 years old. All capacitors wear, and I can't imagine any that are still performing to "as new" specs after 30 years.
Certainly there were some great design (both electronics and exteriors), but I would not be too quick to go for the old stuff unless you (or a close friend) is handy with a soldering iron to recondition such a product.
If it is the look that you are after, Yamaha recently introduced a hi-fi line with a "retro" look which I suspect is a fine and well built unit:
They don't list the specs on their site, so I copied them from the downloadable pdf file:
A-S1000 Main Specifications
[AUDIO SECTION]
Maximum Power (4 ohms, 1 kHz, 0.7 % THD, for Europe) 160 W + 160 W
Minimum RMS Output Power
(8 ohms, 20 Hz—20 kHz, 0.02% THD) 90 W + 90 W
(4 ohms, 20 Hz—20 kHz, 0.02% THD) 140 W + 140 W
Maximum Power
(8 ohms, 1 kHz, 10% THD) 115 W + 115 W
(4 ohms, 1 kHz, 10% THD) 190 W + 190 W
Dynamic Power/Channel (8/6/4/2 ohms) 105/135/190/220 W
Damping Factor (8 ohms, 20 Hz–20 kHz) 160
CD, etc. 150 mV/47 k-ohms
Input Sensitivity/Impedance
Phono MM 2.5 mV/47 k-ohms
Phono MC 100 μV/50 ohms
Main In 1 V/47 k-ohms
Maximum Input signal
CD BAL, 1 kHz, 0.5% THD —
CD, etc, 1 kHz, 0.5% THD 2.8 V
Frequency Response
CD,etc. to Speaker Out, Flat Position 5 Hz–100 kHz, +0 dB/-3 dB
CD,etc. to Speaker Out, Flat Position 20 Hz–20 kHz, +0 dB/-0.3 dB
Total Harmonic Distortion
CD, etc. to Speaker Out 0.015% (90 W/8 ohms)
(20 Hz–20 kHz)
Phono MM to Rec Out 0.005% (2 V)
Phono MC to Rec Out 0.05% (2 V)
Signal-to-Noise Ratio
CD, etc. (150 mV, Input Shorted) 98 dB
[IHF-A Network]
Phono MM (5mV, Input Shorted) 93 dB
Phono MC (500 μV, Input Shorted) 85 dB
Residual Noise CD, etc. [IHF-A-Network] 73 μV
RIAA Equalisation Deviation
Phono MM 20 Hz–20 kHz, ±0.5 dB
Phono MC 20 Hz–20 kHz, ±0.5 dB
Channel Separation
CD, etc., Input 5.1 k-ohms Terminaled 74 dB/54 dB
(1 kHz/10 kHz)
Phono MM, Input Shorted, Vol: -30dB 90 dB/77 dB
Phono MC, Input Shorted, Vol: -30dB 66 dB/65 dB
Bass Boost/Cut (at 50 Hz) ±9 dB
Tone Control Characteristics
Bass Turnover Frequency 350 Hz
Treble Boost/Cut (at 20 Hz) ±9 dB
Treble Turnover Frequency 3.5 kHz
[GENERAL SECTION]
Dimensions (W x H x D)
435 x 137 x 465 mm
17-1/8” x 5-3/8” x 18-5/16”
Weight 22 kg; 48.5 lbs.
They also make a nice CD player to go with it: