frequency generator / counter
You can use several methods:

1) PLL - for example ADF4002 works up to 400 MHz. The resolution is limited, because it works by multiplying reference frequency. This chip will work with your VCO.

2) Integrated PLL synthesizer - ADF4350 can generated frequencies within 137-4400 MHz range with fairly good resolution. However, within your range the result will be more square wave rather than sine. 

3) DDS - direct digital synthesis - AD9910 can generate frequencies up to 400 MHz with resolution under 1 Hz. 

Trying to tune wideband VCO without any stabilization and measuring the result will not provide stable frequency.

Here is a list of PLL chips and PLL synthesizers made by ADI. Other vendors have some too, but usually working within GHz range.