SPI = SCK-MISO-MOSI-Gnd,
I2C is SCL-SDA-Gnd.
The BME280 appears to be a 3.3V interface part.
Turn off the internal pullup resistors (after Begin Wire.h in your code add digitalWrite (SCL, LOW), and digitalWrite (SDA, LOW); where SCL/SDA are pins 18/19 on an Uno, and 20/21 I think on the Mega)
and use external pullups to 3.3V or 5V as needed for SCL & SDA. On the Mega you'll also need to remove of the resistor networks that pulls up SCL & SDA to 5V.
Then you can have 5V SPI and 3.3V I2C.